This Troper considers the comic where Richard, trapped in a void between dimensions, kills his own past and future selves out of nothing more than idle boredom to be the perfect summation of his character.
After being shrunk by Hctib's charm, Richard's emergence from the smouldering ruins of a house: "Rejoice. For very bad things are about to happen." He then makes short work of an entire group of powerful elementals.
Cale gets another on page 241, in which he catches an arrow mid-flight right before it hits Benny in the face, and without skipping a beat, kills the dwarf archer by throwing his own arrow through his head.
He then proceeds to top that feat when Pella admits she's too uncomfortable to kill her own kin by telling Benny to stay out of the fight and killing the dwarves all by himself.
If Cale sealing Tavor in a block of ice and flames doesn't count, then I really don't know what else does.
This Troper found another moment to be Cale's most powerful, displaying why this guy is the world's best hope according to the Ancient Conspiracy. It's not action-heavy, there's no action at all, just the following brief exchange as the party prepares to abandon a village to be destroyed:
Cale: "Stop."
Benny: "The time has passed for us to be gone, Cale."
Cale: "No. We will aid these people, no matter the cost and without personal gain. We are not mercenaries. We will do this because it is right."
Cale: No, it isn't. But it should. And it will again.
Cale along with Sooba show that Mugging the Monster is a very bad idea. Especially awesome as this is the first time we've seen Sooba actually cooperating with Cale alone, even though we might infer that similar scenarios had happened before, way back when Sooba was Cale's sole companion.
Pella gets two: When Richard, a ridiculously powerful and insanely dangerous warlock, tells her that he applauds her (rather snarky) assessment of Cale, but that he doesn't take orders from dwarves, she promptly hacks off his hand and says "Applaud now." And then they laugh about it. And Richard wants to know if they can keep her.
Notably, that was the hand he placed on her shoulder just before. Seriously, don't touch what you can't afford.
Pella slaughters dozens of dungeon guards, which is par the course for Looking For Group thus far. What sets it apart, though, is that she does so with a new custom-forged chainmail outfit, crossbow gauntlets with bladed cuffs, and to the tune of "Lean On Me."
On Christmas Day no less (the strip is from 25/12/2008)