Really, shouldn’t the plural of Eidolon be Eidola? And aren’t they Teralysts that we’re killing? Who knows? Not me. But I THINK I know a few things about hunting those giant, whiny bastards. I also know a few things about leaving them the heck alone.
Just a note, to be able to effectively kill Eidolons, you MUST have completed the War Within. You can’t do this without those pesky space spoilers.
So basically, hunting Eidolons is a massive pain in the ass and only really doable solo if you have an extreme amount of patients and can juggle multiple things at once. For most players, it’s simply easier to find a squad who are farming Eidolons – I recommend the Warframe Raid School Bus for this, even though they mainly do the two Trials (Law of Retribution and whatever the fuck the Jordas Verdict is), they also have lots of people squading up to do other, higher tier missions.
The typical squad contains four key things: a healer, a DPS person, an immunity to status effects and a utility character.
The Healer is generally a Trinity, using a Bless build. The Trinity needs to make sure that the Eidolon Lures don’t die.
The DPS can be any high damage character. Chroma is used a lot due to his ability to deal more damage the more damage he takes, but he’s also tanky enough to not go down in one or two hits, as long as he keeps an eye on his health. I assume Mesa could work as well but since you constantly have to move, she might get left behind.
The Immunity To Status Effects character is generally another healer, either Oberon or Harrow. Oberon’s Hallowed Ground makes everyone immune to the massive magnetic blasts that happen every time you destroy an Eidolon’s limbs and allows you to toggle your healing (while not screwing up a Chroma’s abilities), while Harrow’s fourth ability makes you all invulnerable for a bit and turns any damage you take in the mean time into increased critical chance.
The Utility guy can be a couple of things. Nova and Loki are good choices for stealing Eidolon Lures from Grineer caps and getting them to the battle, while Volt’s Electric Shields protect from some of the Eidolon’s homing attacks and give Operators extra damage.
The battle is a massive mess. And since you have to kill the Eidolon before the sun rises, you need to be pretty fast.
Firstly, before you do anything, find the Eidolon and mark it so everyone can see it (the G key by default).
Next, someone needs to get the Eidolon Lures. There is an Eidolon Lure, a big balloon thing that looks exactly like the drones from bounties, at every Grineer camp. Kill the Grineer, shoot the Lure until it deflates then hack it. You need two drones minimum. Again, it’s worth marking the Lures so you can keep an eye on them more easily, but they’ll have a small blue dot as their icon on the minimap.
After that, you need to charge the Lures. To do this, you need to damage Sentient Vomvalysts until they change into their ethereal forms. You’ll know they’ve done this since they’ll glow blue and you won’t be able to damage them with your guns any more. Bring the Lures near the Vomvalysts and they’ll get sucked up. When the lures are glowing, Onkku of the Quills will tell you they’re charged and you can start the fight against the Eidolon proper.
Before you can actually start harming the Teralyst, you need to remove its shields. You HAVE to be in Operator form to do this. It’s best to stay invisible as much as you can (by toggle-crouching), since Operators die to a stiff breeze, but they are immortal when invisible. You need to use your Void Beam/Amp to break down the Eidolon’s shields. This is where Volt comes in handy, his Electric Shields are one of the few things that can increase the damage of an Operator’s void powers.
The Eidolon will have various attacks. One slam attack works like the MOA slam attacks, and you can jump over the shock wave. The other slam attack will throw you around like a rag doll if you get too close. The volleys of blue projectiles can often by dodged by rolling out of the way. Rarely, the Eidolon will call down a barrage of missiles – the only way to avoid this is to switch to Operator Mode and remain invisible until it’s over.
Once the shields have been removed, you need to shoot out a limb. Coordinate with your team mates so you all work on one limb and destroy it before the Teralyst’s shields return.
When a limb is destroyed, the Eidolon will fall to the ground and cry, letting out a huge magnetic blast. Onkku will warn you in advance. If you have a Harrow or Oberon, huddle around him. If they’re too far away or you don’t have one, leg it and get out of range.
Eventually the massive magnetic blast will end. You’ll need to repeat the process with the other limbs of the Eidolon.
If your Lures are still alive, they will latch on to each of the Teralyst’s damaged limbs. Once you have broken them all, the Eidolon will fall to the ground and start screaming for help. At this point, tons of Vomvalysts will start to appear. You have to kill as many of them as possible to stop them from healing the Eidolon.
After a while, the Eidolon will start to fade away, its energy captured by the Lures. Eventually it will disappear completely, the Quill will congratulate you, and you’ll be left with a lot of sentient cores to pick up. Make sure you pick up the sentient cores AND the Eidolon Shards, which can later be turned into extra points for your Focus, to be used for upgrading your Operator.
Keep in mind that you have until BEFORE the sun rises. The Quills will warn you that the sun is rising and the Eidolon is retreating, but that’s very rarely enough time to actually capture the Eidolon. The Lures will also randomly explode not long after the warning. Which is annoying.
After an Eidolon is killed, you can use an Itzal archwing to instantly suck in all nearby loot. You’ll want to get to extraction quickly, as many squads will want to get back, reset and restart in order to hunt the next Eidolon as quickly as possible. A good team can get 4-5 Eidolons in a single evening, but don’t worry if you only manage to capture a couple. There will always be more nights to capture Teralysts.
When it comes to leaving the Eidolons alone though, that’s really simple. Just stay away and don’t shoot it. Oh, and don’t fly near the Eidolon with your Archwing. It will get pissed off and shoot at you, mistaking you for some sort of massive, ugly, infested insect. Doubly so if you’re playing Titania. Small problem, the infested wandering around due to Plague Star have a habit of triggering the Teralyst, but I don’t know if they’re permanent yet.
Luckily, if the Teralyst is angry, that’s not a problem. Just find somewhere to shelter in the opposite direction to where it’s going. The Eidolons have a habit of following a fairly set path, so you don’t need to worry too much about it chasing you down.