YMMV / Iron Marines

• Anticlimax Boss: For a supposed Final Boss at the game's release, Mr. Rob070 can be beaten quickly and easily if you just amass numbers of Channelers. Once you've got four groups of Channelers, they'll put out so much damage to defeat his first and second phases (remember to use the Drop Turret to distract the Inductors in Phase 1 and the large robots in phase 2). As for the third phase, it becomes ridiculously easy with Channelers, since they're the fastest unit in the game and can easily outpace Rob070's Chasing Your Tail lasers with extreme ease by just doing a group-select on them and moving them away, and they'll drain his health away in short order.
• Demonic Spiders: There are a good number of enemies that pose a pretty huge threat:
  • Taskmasters have a good amount of health, massive amounts of armor, constantly spawn Oculi, have a painful AoE against your strong Melee units, and count as structures. This means that snipers, Channelers and non-armor-piercing attacks don't do much to them, they're immune to instant kills and are very tough in durability against most things. Fortunately Engineers can take them down with ease, thanks to having a Chain Lightning that fries the Oculi, and thanks to the Taskmaster being a structure they will also deal very heavy damage to it and keep it stunned with their structural sabotage grenades.
  • Surge Protectors have a very painful splash damage bomb attack, and it can give themselves and nearby Peripheroids a Forcefield that grants temporary invincibility. They also have one of the highest HP values of any normal enemy in the game and high armor meaning that it's hard to take them down fast, unless you use instakill-chance attacks.
  • The tentacle aliens in the second-to-last level of Ascendaar. Not only do they hurt about as much as the Fell Bishop, they also have a good bit of health, are immune to the otherwise powerful melee attacks thanks to popping up from the slime areas, and worst of all they constantly respawn even if killed.
  • Raad Carriers don't do anything by themselves. The problem arises when a Raad gets near them, after which it boards them and becomes a fast, powerful Airborne Mook — and are oftentimes already spawned with a Raad inside. When any of these are killed, the Raad pilot ejects and you have to fight that too, meaning that simply spamming Shellstorms to take care of the Carriers isn't a 100% viable tactic here. Finally, Carriers tend to be spawned in groups if they're spawned naturally with a pilot, meaning that you have to take down a big group of painful airborne units and then take care of the guys they leave behind.
    • Ionic Carriers have a Charged Attack that hurts a lot but is interruptible (more problematic than it sounds thanks to their long range)
    • Pyre Carriers will burn units near them with a constant damage flamethrower.
    • Grav Carriers create damaging and lingering areas on the ground just like Blightmothers. Unlike Blightmothers who usually appear in ones or rarely twos, these can appear in greater numbers.
    • The worst by far are Quantum Carriers which fire very slow portal balls... that do extremely painful, armor-piercing constant damage if they get in contact with your units, and then explode a wide area for even more massive damage. Not even a Diplomat's shield can save most units from the portal balls before it expires, and while they're avoidable by moving out of the way, you're out of luck if the unit is a slow-moving mech or an immobile turret. Finally, they drop an irritating-to-fight Tachyon Elite when killed.
• Difficulty Spike: Mission 4 is generally considered a huge step up in difficulty and acts as a wake-up call level. You need to protect your base on three different fronts, and once those three enemy bases are captured you will need to hold them for 2 minutes where neverending swarms of mooks keep heading towards them, including Hammergrubs.
• Game-Breaker: Enough to fill a page.
• Goddamned Bats: So many that they have their own page.
• Heartwarming Moments:
  • Invasion reveals that the Ascendii have returned to their former numbers after being reduced to a single member in the previous game. Not only that, they're now playable and Ascendaar itself has not just been restored to its former glory, but also became the Federation's hub city!
  • Invasion also reveals that the Fell have made peace with the Federation and are now steadfast allies capable of fighting back against their former oppressors, the Raad.
• I Knew It!: Many speculated that the Eldritch Abomination seen in Invasion's trailer was the same entity as The Overseer from Legends of Kingdom Rush, having a green tentacles and yellow Giant Eye of Doom design. When the game was released, the Void Sovereign's bio confirmed this theory.
• Low-Tier Letdown: Sha'tra is generally considered one of the worst, if not the worst Hero in the game. His attacks don't do much damage compared to several other heroes and while he does have a guaranteed instant kill in Abduction, it has a long cooldown and cannot affect structures.
• Scrappy Mechanic: The "targeting" mechanic introduced in the third world. In order to destroy obstacles and other things like unmanned Raad Carriers or Raad Portals, and reveal Alpha Fenrir stealth you need to tap on the object/enemy, otherwise your troops or heroes will ignore them completely. You can only target one object/enemy at a time, the hit detection is poor (you might target something else instead), and sometimes your units refuse to fire at the targeted object. All this makes Nexus, especially his final phase quite the agonizing fight since this mechanic is key to disrupting or surviving several of his That One Attack.
• That One Attack:
  • The Overseer's Macross Missile Massacre. Not only can it be used from a long distance when it takes to the air and retreats from your units, it deals a massive amount of damage to troops and heroes. Unlike the Fell Bishop's Super Spit attack which is an avoidable splash damage projectile, this is pretty much unavoidable thanks to being homing missiles. The Overseer's other attack is a claw slam which is only used when it's grounded, but this can be easily tanked by a Brawler which makes it far less devastating.
  • One of Nexus' hand attacks, specifically the one where he turns blue, can be a lot more dangerous than the others, and it's even the first move he'll attempt to open up with. He'll fire a load of meteors into the air that will hit certain spots around your Tortugon, and each is a One-Hit Kill — if you fail to move the slow-moving Tortugon out of there, you lose. Even if you did manage to dodge it, they'll leave behind obstacles that block the Tortugon's way and must be targeted if you wish to to destroy them. Since you will most likely be targeting Nexus, the purple devices he drops, or his hands, this makes the meteors quite frustrating to remove, and worse still, the meteor attack can sometimes land in a way such that your Tortugon cannot avoid it causing an instant defeat. Thankfully, you can disrupt this attack by targeting his hand and hitting it enough.
  • Nexus' other nasty attack occurs in his final phase where he drops 3-6 (depending on difficulty) purple devices with a timer countdown around your Tortugon. Firstly, you need to target them in order to destroy them before they activate, and you can only target one at a time. Secondly, this attack cannot be disrupted unlike Nexus' single-hand attacks. Third, if you fail to destroy any of them before time's up, it turns into a large, slow-moving, lingering purple ball of energy that deals high continuous damage on contact with your units then explodes for even bigger damage after a long while, and each ball will be aimed directly at your Tortugon. This, along with the Tortugon's incredibly slow speed as well as the fact that you lose if the Tortugon is destroyed, makes it a very frustrating attack.
• That One Boss:
  • In terms of miniboss enemies, Peripheroid Overseers are far more dangerous than Fell Bishops. They can fly quickly every now and then while attempting to flee from your units, and when airborne they use a Macross Missile Massacre that deals tremendous damage from a long distance and can hit wider groups of troops compared to the Fell Bishop's Super Spit. All this makes the tactic used against Fell Bishops (stunlocking with Diplomats and grinding them up with Guardians) fall flat and requires the use of Shellstorms to do good damage to them and a Brawler to tank. Finally, they have gigantic amounts of health just like the Fell Bishop. Thankfully, they're only found in two Brutal Bonus Levels after you beat the main campaign, but they certainly are deadly when encountered each time.
  • Nexus is a lot more difficult than the Fell Tyrant or Mr. Rob070 thanks to being three Escort Missions with a Poor Pace Escortee. Firstly, Nexus retreats into a portal and regenerates a short while after he's killed. You have a very slow-moving but somewhat durable turtle mech unit each phase that must enter that portal to destroy it before Nexus regenerates, and you have to do this three times, each time causing Nexus to use far more dangerous attacks. If any of the turtle mechs dies in any phase, you fail the mission. Nexus will fire a Knock Back energy blast at the nearest unit to him, and most of his elemental attacks if not interrupted via targeting his hand will target the Tortugon and some can outright One-Hit Kill it such as the rain of meteors. The worst is the final phase, where he'll be accompanied by Demonic Spiders that fire slow-moving purple balls that do painful constant contact damage (not helped by the Tortugon's slow-as-molasses speed), he can unavoidably Life Drain all your units on the field putting you on a timer, and he also summons destructible devices with decent health around your Tortugon that must be targeted one by one, and if not destroyed will detonate into said purple balls aimed right at your Tortugon. On Normal, he summons four. On Impossible mode, he summons six. Basically, prepare to move around all your units a lot, use the unreliable targeting to prevent the dangerous moves, and even then if he manages to pull off the meteor attack where it hits an area your Tortugon can't avoid, you're still out of luck. The only silver linings are that you get a new Tortugon with full HP each phase and that there's toolkits that periodically drop which will heal the Tortugon.
• That One Level: The Special Ops Mission "Laser Tag". This mission throws aside all strategy with heroes and units. Your goal is to maneuver a dropgun with legs around an arena for three minutes where Suppressors attempt to take it out from offscreen, and if any of them successfully fire a shot it's a One-Hit Kill and you fail the level. In order to shake off the Suppressors, you either need to bring the dropgun to the opposite end of the arena, or have one of the 5 pillars block their line of sight. Said pillars will ascend and descend in a seemingly random manner meaning that you cannot always rely on them. Later on, the game also has a random chance to throw in some Nortrons to make things even dicier. If that's not enough, there's an achievement for completing this level without taking any damage, meaning that you cannot afford to let the Nortrons get anywhere near the Dropgun.