Several enemy units in Iron Marines are far more irritating than others thanks to unique abilities, but don't pose a major threat unless they appear in huge numbers.
- Spitterbugs attack for pretty good damage from a long range, and their attack pierces armor. They also have quite a good bit of health for sniper-type enemies. Dropping the dropgun on them is highly recommended.
- Etherleeches don't attack squads nor deal damage. What they do, however, is to shoot stunning balls at your towers, before draining your precious Etherium resources from stunned towers. They're Airborne Mooks, meaning that melee is not an option, and even get bonus goddamned bat points for actually looking like bats. Fortunately, missiles/rockets put them down extremely quickly.
- Mindbanes have a very fast dash ability to close the distance to your units, before attacking with an medium-area shockwave around them for good damage. While not too durable and unarmored, they also appear in good numbers racking up damage with their AoEs.
- Jackbots appear in large numbers, have far more health than the weakest Fell aliens due to being Peripheroid robots, and have the ability to increase their firing speed if they are in a group. Their attack may be weak but it pierces armor, leading to Death of a Thousand Cuts by a group of them. Furthermore, other Peripheroids can affect them in various ways beneficial to them.
- System Monitors. The Mook Medic and The Engineer of the Peripheroids, these can do three irritating things — repair Assembly Centers, heal Jackbots, and finally have a long range unavoidable Splash Damage homing missile attack. They have rather low health and lack armor, thankfully, but they tend to hide behind Jackbots, Nortrons and Oculi which makes shooting them first irritating.
- Spammers are Airborne Mooks with only one ability — spawn Inductors in groups. While Inductors are very weak units with a not too strong close range area attack and a temporary invincible state when not attacking, their potentially dangerous trait is to overload the wreckage of fallen Peripheroids, turning those into time bombs that explode for heavy damage. Furthermore, Spammers are also very cowardly and will attempt to escape from battle if attacked so they can heal up and try to drop more Inductors again.
- Suppressors are the Peripheroid counterpart to your Snipers and thus have extremely long range while dealing massive damage. One shot from them is enough to One-Hit Kill anything that isn't a Brawler. Thankfully they have low health, don't appear too often, have to lock on for 7 seconds before attacking and abort their attack if a unit moves out of range or gets blocked by terrain.
- Ion Troopers are the most basic and common Raad units. While they're not too painful nor durable, they appear in decent numbers and can use energy shields to make them tank damage. Most frustratingly, killing a single one will make it explode into energy that makes other Raads nearby heal a huge amount of health over a short period. This makes killing groups of them quite a chore if you don't take them all out at the same time or use high-power attacks (like Dr. Graaff's suicide drones or Blue Dragon's Ultrablast) to remove them instantly, since the others will get healed and activate their shields which prolongs the fight.
- Pyron Guard Raads have a long-distance fireball attack that causes splash damage and burns all targets within the splash, making them lose health over time and unable to regenerate until the burning stops. When killed, they explode in a rather large radius dealing big damage while also burning your units within the blast, which forces you to actively move away your melee units (which are effective against them).
- Fenrir have a basic Zerg Rush strategy, which combined with their fast speed and far greater numbers than even the Fell make them irritating to face especially if you need to take care of both them along with Raad Carriers in the same level. Shellstorms and Missile turrets will destroy Raad Carriers but be torn to shreds by the massive Fenrir numbers due to slow fire rate, while Flamewalkers will torch packs of Fenrir (and make them run wildly without attacking) but is useless against the flying Raad Carrier.
- Alpha Fenrirs are also quite a huge annoyance. They aren't too durable but they are fast and very painful... when they're not stealthed. If they're stealthed, most units won't see them and their attack deals MASSIVE damage to anyone it hits — enough to One-Hit Kill or two-shot some of the tankier ranged heroes such as Mark X, for starters. Furthermore you have to actively select them if you want to de-stealth them too which causes more micromanagement. Fortunately, they make their presence known by giving of a snarl/howl whenever they spawn, and they aren't as effective against melee units.
- Tachyon Elite Raads have space-time abilities which they use to Teleport Spam every few seconds or when they take enough damage, and fire a painful Pinball Projectile that bounces across many units. They're only as durable as the basic Ion Troopers, but the annoyance doesn't end when they're beaten because they spawn a Raad portal on death. Even their Flavor Text lampshades how irritating they will be:You don't know what true frustration is until you have tried to kill an Elite.