MacGuffin: The Gates. Xykon even refers to them as such. Redcloak discusses this trope in "I Think I Left It in the Bag..." (spoilers!), noting that the MacGuffins aren't the only things that matter in a battle.
Tarquin: In any race for hidden treasure, it is always the protagonists who sweat and bleed and die to overcome the many challenges inherent in finding it, only for the antagonists to seize it from them at the last minute.
Magic Feather: Enor, the blue ogre/dragon hybrid, is given a piece of lizardfolk Victory String by Gannji to give him courage in battle (it's just a piece of string, of course). Roy lampshades this trope when Belkar points it out. Belkar tries to give him a "halfling Courage Rock", but Roy won't take it, and instead suggests Belkar keep it someplace safe. And dark.
Make-Out Kids: Once they get together, Elan and Haley tend to have difficulty keeping their hands off of each other, so much so that announcing they are going to have sex is actually a quite believable excuse. After the siege of Azure City, what was meant to be a see-you-soon kiss quickly devolves into tearing each other's clothes off in front of everyone, before they're reminded that they have jobs to do.
Strip #688, the Order's reaction to the giant worm bursting out of the desert.
Strips #825 and #826, when the Resistance party discovers that the enemy found their hideout, and that Redcloak himself is there to welcome them, with several high-level summoned creatures at his side, and all the other members of the Resistance dead.
Roy, Haley and Elan in #885, when Xykon appears out of nowhere. Ironically, Xykon says the phrase, but the protagonists are the ones who fit the spirit of the trope.
Jirix is a villainous Mauve Shirt. His name had been mentioned on multiple occasions before O-Chul killed him during his escape from Xykon's imprisonment, and he was deemed important enough that Redcloak resurrected him (at Xykon's demand). Redcloak then appointed Jirix the prime minister of the sovereign nation of Gobbotopia (built on the former site of Azure City).
Suitably for an air elemental, Celia's name means "heavenly" in Latin.
Blink and you'll miss the etymology behind the chimera Trigak's name. It is the sound he makes when Belkar slays him: all three heads crying "GAK!"
Argent the wolf is named after the French word for "silver", and he has silver-lined fangs that make his attacks more deadly towards devils. Lampshaded: the strip this fact is introduced in is called "His Name Probably Helps, Too".
Tarquin is named after Lucius Tarquinius Priscus and Lucius Tarquinius Superbus, two legendary kings of Rome. The former was a foreign commoner who charmed his way into power and ruled as a benevolent dictator, while the latter was a scheming and malevolent despot whose overthrowing heralded the beginning of the Roman Republic.
Characters are also explicitly aware that their setting operates on Dungeons & Dragons rules and mechanics; even the comic's first strip depicted their reactions to being upgraded from the 3rd to 3.5 edition ruleset mid-battle. (Word of the Giant has it that the comic will not be upgraded to 4th edition rules.) References to Hit Points, skill checks, dice rolls, experience and class levels, spell slots, etc. are ubiquitous throughout the comic.
To combine the two above examples, a dwarven assassin points out to his Shadowdancer companion that his "shadow jump" ability is useless because this is a stick figure comic with no shadowing.
Mercury's Wings: One of the paladins guarding the Azure City throne room has winged boots allowing flight.
Milholland Relationship Moment: Sort of played with in a villainous example in "Not Much Chance of That". After Malack blasted Tarquin and the rest of the Order with a Flamestrike spell when he grew impatient of Tarquin toying with them, he delivers a blistering tirade about how Tarquin demanded he put his personal vendetta against Nale aside, but Tarquin was wasting time in order to assess Elan's growth in battle. Sabine even lampshades to Qarr about how Malack and Tarquin are about to "get into it". But after Malack has finished ranting, Tarquin takes a moment to think and sincerely apologises to him, admitting Malack is completely right and he didn't know what he was thinking.
Roy: Isn't a "brontosaurus" really just an apatosaurus with the head of a different dinosaur? Tarquin: And a hippogriff is really just a horse with the head and wings of a bird, but I've still got eight squadrons mounted on the damn things. Roy: Hmm. Fair enough.
The Mole: Redcloak manages to infiltrate the Azure City Resistance by polymorphing a hobgoblin into a human.
The prize goes to Start of Darkness: while Right-Eye is blasted from the sky and Xykon literally drains Dorukan's life-force away, the Monster in the Darkness decides to hold a taco fiesta. The well-executed switches are often cited as one of the comic's main sources of appeal.
The latest book alternates between V condemning him/herself to hell to save V's family and the Three Archfiends making college jokes.
One small example: Miko and Redcloak are fighting in one of the towers at the Azure City borders. Redcloak has managed to hit Miko hard enough to make her drop her katana, and he asks for Xykon's help... upon which we see Xykon placing a bet on the fight's outcome with the Demon-Roaches — he bets on Miko winning — while the MitD has a popcorn bucket and a giant hand, supporting Redcloak as one would support his football team.
The comic titled "Yes, Apparently" pulls off a rather jarring one. It takes five panels for Elan to go from hugging his dad in a heartwarming moment to realizing that his dad is burning thirty people alive.
After a while, one gets used to Xykon being an affable, lazy tyrant content to crack jokes and lounge about while Redcloak runs his army. Then Soul-Spliced Vaarsuvius pushes his Berserk Button. The immediate change in attitude is jarring, to say the least.
After Tarquin orders his giant army to kill the whole Order of the stick minus Elan and Haley in "Executive Order":
Belkar: Can't we go back to dealing with [Roy's] daddy issues?
Mooks: One of the comic's themes seems to be to deconstruct the concept. Gods Need Prayer Badly, so goblins were explicitly created to be low-level fodder for their clerics to gain XP. The comic's main plot is driven by the goblins (especially their High Priest) rebelling against the gods who forced them into this role.
Moral Dissonance: Intentionally. Moments like the slaughter of Redcloak's village and the brutal execution of a hobgoblin prisoner from Azure City by the Elvish liberation forces remind us why Redcloak is on his crusade, and lead us to wonder if he might not have a bit of a point.
Belkar: Stupid cat. A ranger is supposed to influence an animal's behavior. You're doing it backwards!
O-Chul for the Monster in the Darkness. It did help him escape, after all.
Blackwing invokes this. He now works as a sort of conscience for V.
Moral Myopia: A vicious cycle: the gods consider the goblins nothing more than XP fodder; this leads the goblins (and hence Redcloak) to decide that humans are fair game to kill also, leading to a Cycle of Revenge.
Mugging the Monster: Repeatedly mocked. Crime does not pay in this 'verse — inevitably, a low-level thug will try to take on a high-level adventurer and end up reduced to a meager handful of XP and GP.
Xykon: ...and it turned out oops! He was also an archmage! Needless to say, hilarity ensued.
Multiple Choice Form Letter: In Start of Darkness, although Eugene Greenhilt correctly switches the part of the Blood Oath saying "Insert Target Name Here" with Xykon's name, the halfling tattoo artist carving said oath clearly implies it isn't always the case.
Roy: Hey, you know, we're all enjoying this luxury, but we should at least share it with the others. We should get Vaarsuvius and Belkar up here. (beat panel) Roy: We should get Vaarsuvius up here. Elan: Yeah, definitely! Haley: Sure, let's get V in here. Durkon: Aye.
In "We Can Do This the Easy Way...", Roy talks to Xykon about why he has to take him down now, instead of taking the lich up on his offer to be released from the battle and level up for a few years to make it a better fight:
Roy: You may not be out to destroy the physical planet, but living under the heel of a walking villain cliché like you will destroy its soul. If I don't beat you here and now, then soon this nonsensical screwed-up world won't exist anymore. There won't be any place left for introverted dwarves. Or androgynous elves. Or idiotic bards or greedy rogues... or sexy sylphs. Or hell, even raging narcissistic paladins. Bloodthirsty halflings will probably get along fine, though.
Redcloak gets to do this twice: once when he realizes how stupid his bigotry towards hobgoblins is, and once in the prequel Start of Darkness, after he kills his brother Right-Eye.
Vaarsuvius, after the Soul Splice. Subverted at first — since V considers the black dragons to be Always Chaotic Evil, the elf is more remorseful about the Deal with the Devil itself, and the wasteful use made of it, than the Familicide spell itself. However, upon discovering how the Draketooth Family died — and further realising that countless other humans could have been killed by the spell — V goes into a full-blown Heroic BSOD.
Belkar: I sense a great disturbance... as if a thousand double entendres cried out, and were suddenly silenced...
My Species Doth Protest Too Much: Zz'dtri uses this to justify his presence, claiming (through Nale) that due to imitation of a certain Dark Elf ranger his entire race is like this now. He's lying, but the Order buys it.
Myth Arc: Roy and the Order's quest to destroy Xykon once and for all — and, once they discover their significance, to secure the Gates if possible. Villains other than Xykon (for example, Nale and Kubota) are actually referred to in dialogue as "side quests".
Narrator: Spoofed in the prologue to the print volume of the first arc.
Never a Self-Made Woman: Deconstructed, and then reconstructed. Haley Starshine essentially has her father to thank and to blame for everything in her life; he taught her to be a fantastic thief by teaching her to mistrust everyone, and the only reason she joined an adventuring party in the first place was to raise money to pay his ransom. By the time she resolves her issues with her father, by realizing that Ian's paranoia and trust issues were poisonous and that she needed to move on, because it made it impossible to open up to the man she loves, she's already in a relationship with Elan, and now her personal issues revolve around learning to open up to people (naturally, with Elan's help).
Vaarsuvius: I have a plan. Blackwing: Does it involve selling your soul? Vaarsuvius: No. Blackwing: Really? Vaarsuvius: No! I mean, yes, really. It involves coordination. Blackwing: Coordinated soul-selling? Vaarsuvius: NO! Blackwing: Is that a "maybe"?
Also, the destruction of Lirian's Gate in a forest fire seems to be this for Redcloak.
Redcloak: Look, it was an accident! OK? Let it drop already. Geez!
Hinjo: I see. Then you were the one who made the decision to destroy the Gate rather than let it fall into Xykon's clutches. O-Chul: I did make that decision, and it was my blade that did the deed. (I shall say no more about it, lest I speak ill of the dead.)
Basically, the whole point of the fourth completed arc. Some bad things happened. The compilation book, containing said arc, is titled Don't Split the Party.
And then they did it again, resulting in Vaarsuvius, Haley, and Elan getting captured by bounty hunters.
New Rules as the Plot Demands: Rich Burlew claims to follow this pattern, but he's usually actually very good about replicating D&D's rule system in a believable way. Some of the few straight examples are the fact that goblins and sprites are medium-sized and Always Chaotic Evil races are more Punch Clock Villains. As one might expect, it doesn't exactly hurt the comic.
Miko actually does this twice. Once when she kills Shojo, resulting in her being stripped of her status as a paladin (and all the benefits that go along with it) and creating a power vacuum that results in Daimyo Kubota's forces spending more time trying to assassinate Hinjo than defend the city. And, again, by destroying the sapphire in the throne (and Soon's gate trapped within it) as Xykon is about to be re-killed by the ghosts of the Sapphire Guard, thus causing the ghosts to dissipate.
In Start of Darkness, when Xykon is confronting Lirian, he doesn't know that there are four other gates until...
Lirian: Even if you locate them, my friends will stop you from conquering the other four Gates. (beat panel) (beat panel) Xykon: Did you— Did you just say, "the other four Gates"? (beat panel) Lirian: Crap.
Redcloak, after holding a group of Azurites hostage during one of his interrogations of O-Chul, decides to let them live, hoping that they'll spread word of how the (seemingly) last Sapphire Guard was willing to let them die, which will break the will of the other prisoners. However, this backfires big time, as they instead interpret events as a member of the Sapphire Guard having survived the battle and still heroically resisting the enemy's attempts to break him (which is true), which raises the hopes of the prisoners.
Nale takes an opportunity to pre-emptively kill off Malack, depriving Tarquin of one of his greatest allies. This also allows Vampire!Durkon, who now appears to be considerably more powerful, to regain his free will, effortlessly kill off Zz'dtri, and side with the Order of the Stick once more.
The Fiends call in Vaarsuvius's debt with them, and while their soul is in hell their body is magically protected from all harm... allowing it to survive the destruction of Girard's Gate.
The best example would probably be the diamond from the cast page, which Haley stole from herself in order to pay for a spell in the main comic.
In one strip, a mute Haley holds a mental argument with herself while on the road, drowning out Elan's Blah Blah Blah dialogue. In the final panel, it's revealed that he's literally been saying "blah blah blah" the entire time, hoping to set a new world record in consecutive use of the word.
In the comic book compendium of this webcomic, the party uses the narrator to distract the monster guarding the entrance to the dungeon.
Lien knew that Qarr was up to no good from his sinister-looking Speech Bubbles (red text on a black background).
It's possible to feign death by drawing X marks over one's eyes and lying very still.
Most of the characters seem aware that their world works on RPG rules and occasionally refer to the fact that they're in a comic, but Roy seems thoroughly confused when the Oracle goes even further and directly addresses the readers.
Tsukiko is level-drained to death by wights, who are then commanded to eat each other one by one until the last remaining one sets itself on fire. This is partly to make absolutely sure of the death and Leave No Witnesses, and partly to illustrate just how different Redcloak's opinions of the undead are to those of Tsukiko, who goes out begging her "babies" to stop "hurting Mommy".
Mentioned as early as strip #21, where Haley complains that the fact that they killed a named chimera implied it should have become a recurring villain.
Lampshaded by Kazumi and Daigo, two Azurite soldiers, who go from Red Shirts to Mauve Shirts just by revealing their names. (Daigo, observing the power of this effect, wisely decides to save his last name for a future emergency.)
Non-Combat EXP: The first time the Order levels up on-screen, Belkar, their psychotic evil halfling ranger, is a mere handful of XP shy from leveling up with everyone else. When killing rats proves to not grant XP and party kills are banned from him, he resorts to pulling out a sob story for roleplaying XP.
Belkar: 'mfine. Halfings may only be able to advance to level 8, but I've got Attack Rank G. Guard: That boy got his ass knocked back to Basic!
Noodle Implements: Elan and Thog's plan to get back into Azure City apparently involved a corkscrew, skis, a basketball, a box of soap, a traffic cone, a leprechaun costume, and a giant wooden alpaca full of potato salad. It should be mentioned that the costume was, for several comics, all we saw. The rest of it showed up in a comic titled "As Good an Explanation as is Forthcoming" which, of course, only raised further questions.
Lien: My parents were fishermen. When I was a little girl, I stood right here and learned how to clean the fish that they caught. I'm telling you this so that you know that when I say that if you take one more step, I will gut you like the catch of the day — IT IS NOT HYPERBOLE!
In "Rapier Wit", Belkar states that he could sunder Elan's rapier by speaking too loudly.
It appears that one of these was the last straw in the marriage of Elan's parents.
Tarquin: You sound like your mother. "Oh Tarquin, you jerk! When you said that you would liquefy every man in the tavern if one of them grabbed my butt again during my shift, I didn't think you meant it!"
Not Right in the Bed: The evil twin variant is used when Elan, a good-natured naïve bard, is framed and swapped with his evil twin brother Nale, who proceeds to attempt to woo Haley (with aims to murder her at the height of passion), since she had up to this point had a hidden crush on Elan. Haley notices the startling change in behavior, including the initiative he takes in arranging a romantic date, but ignores her instincts (and that of her inner personalities).
V and Belkar have always opted for a brute force style in facing their problems, but thanks to Character Development, they've also seen other ways of looking at the world. To drive the point even further, they both have dark fates in store. Belkar is slated to die before the end of the year, while V is indebted to the service of the IFCC for 44 minutes and 16 seconds.
Nale and Tarquin. When rejected by family members, they both react by stabbing the rejecter. They also think that anything that happens near them is about them.
Played with in "A Familiar Face", when Celia recalls finding out her boyfriend "slipping the wood" to a dryad. He says it's not what it looks, but it's unclear what it looks like in the first place....
Subverted when Nale seduces Haley in order to betray and kill her, only to be stopped when his enraged girlfriend Sabine arrives. She realizes what's going on immediately, but wanted to kill Haley herself:
Nale: It's not what it looks like. Nale: (simultaneous) I was going to KILL her. Sabine: (simultaneous) YOU WERE GOING TO KILL HER!
The Nudifier: In one of the Dragon Magazine strips, Belkar takes delivery of a Wand of Dispel Clothing.
"Inverted" with the IFCC's adress, which is "9 Hells Plaza, Lower Planes 00999".
Number Two: Haley is briefly mentioned as being Roy's second-in-command during the battle of Azure city. She's not too confident about her abilities in this regard, having suckered Roy into naming her second-in-command in the first place in On the Origins of PCs only for a bigger share of treasure.
Occam's Razor: Redcloak and O-Chul disagree over the application of this principle in a strip entitled "O-Chul's Razor". While not brought up, Redcloak is also defying Hanlon's Razor in assuming that the Sapphire Guard were being devious geniuses rather than blinkered fools.
Roy at last complimenting Elan for doing a good job (after snapping the party out of Girard's phantasm) and apologizing for having yelled at him earlier makes Elan think they are still trapped in an illusion where his fondest dreams are coming true.
Roy is rather unnerved when Belkar, Constitution-drained and fragile, starts behaving like an actual ranger in their battle with Tarquin, using Wild Empathy to control the enemy's battle dinosaur instead of just leaping into hand-to-hand combat.
Roy: Okay, now I know we're doomed. Belkar is acting like a ranger.
Ooh, Me Accent's Slipping: Durkon, once he becomes a vampire. Lampshaded in his first conversation with Hel: his vampiric self is deliberately putting the accent on in order to seem more like his old self.
Opponent Switch: Done by the villains in the first Order-vs.-Linear Guild fight: Nale and Thog swap opponents (Elan and Roy) to avoid the Fearful Symmetry of fighting their own opposite numbers. It doesn't work, since Elan's magic actually works on Thog and Roy's ecstatic at the chance to whale on someone who looks like Elan, since he was still The Load then.
One of the few cases in which it is satisfactorily explained. When the main characters first encounter Xykon, he is sitting around his throne room doing nothing much. We come to find out that this is purely because the Gate he wished to access can only be opened by "one who is pure of heart," so he has literally been held up by a lack of adventurers.
Later, after he conquers Azure City, he spends the entire "Don't Split the Party" storyline sitting on his butt in his castle torturing a captured paladin. Turns out, this was all Redcloak's doing: he's been deceiving Xykon into not leaving until the hobgoblins have solidified their hold on the city. Xykon loses patience with this when his phylactery gets lost, taking Redcloak's eye (or rather forbidding him to regenerate it) and commanding that they leave immediately after finding the phylactery. Now Redcloak appears to have no intention of giving it back, using a substitute.
The gender of Vaarsuvius and V's mate and (adopted) children.
The Monster in the Darkness' identity.
Our Dwarves Are All the Same: Lampshaded in "Clerical Temp". Durkon Thundershield fits the stereotype perfectly, including the combination of Norse Mythology and Scottish accent. When the party is split and one half hires a cleric to magically contact Durkon, the cleric gets an accurate description and then asks what sets Durkon apart from every other dwarf in existence. However, they are known to have odd anatomical features such as two livers. (Though that may be just natural selection in action.)
On the other hand, it should be noted that Durkon is calm, introverted, mild-mannered, and makes use of his spellcaster abilities as often as his weapons. He takes his job as a healer very seriously, not limiting it to use of magic (he has significant medical knowledge, as seen when he's examining Haley and giving advice to a pregnant woman). All this sets him very much apart the usual drunken, axe-throwing and curse-spewing stereotype, making this more of a Zig-Zagging Trope instead.
The elves aiding the Azurite resistance are, with their "the only good goblin is a dead one" policy, walking justifications for Redcloak's behavior.
Aarindarius, V's master, is apparently powerful enough to take on a full adult black dragon without looking away from the book s/he's reading, though this was according to Vaarsuvius in the middle of an arc throughout which V's judgement was severely impaired.
The first vampire we are introduced to is Malack. Unusual in that he's a Snake Person rather than a humanoid. Also, he demonstrates the ability to bend D&D rules for vampires — he can talk in his vapor form and, when creating another vampire, use his staff to shorten the reanimation process so the whole "buried for 3 days" rule doesn't apply. He also has a custom-made Protection from daylight spell.
Strip #946 reveals that vampires (or at least Durkon and possibly any other vampirized dwarves) are controlled by a foreign evil spirit while the original spirit is trapped helpless in the same body.
Outscare the Enemy: Tarquin combines this with I Have Your Wife in order to keep his army in line; his soldiers know that while the enemy might kill them, Tarquin will slaughter their families if they displease him.
Overused Copycat Character: Spoofed when Nale claims that every drow in this world is like Drizzt Do'Urden now. This is soon shown to be untrue when it's revealed that the Linear Guild members are evil, and the only other drow we ever see* (one of the adventurers who attack Roy in the afterlife) is also evil. V takes advantage by getting Zz'dtri hauled away by copyright lawyers.