Etrian Odyssey 4: The Heavenbringer (5 Imperials)

If you think 5 Imperials can outdps race the Heavenbringer easily, think again. This took quite a few attempts to pull off.

The limitations of the Imperial becomes a lot more painfully clear when an enemy actually manages to survive their assaults. Normally your other party members would be able to cover for an Imperial's downtime while they're using Heat Sink or their edge skills. But when your other party members are also all Imperials... This resulted in me actually having to use Ignition, and unironically use Overdrive to deal with Heavenbringer's hands. (When in most other cases with a party with an Imperial in it, the enemy would most likely be long dead before Overdrive comes into play.)

Heavenbringer really asks you to bring your best crowd control tools. Which Imperials don't have a lot of. No disables to slow her or her limbs down. And very limited ways of dealing AOE damage. And the limbs are about as durable as an FOE from a bit earlier in the game, so they're not just targets you can take down THAT quickly. Heavenbringer hits really hard and her hands can slow your party down, letting the fight spiral out of control the longer you leave the limbs alive. After destroying both of the limbs, Heavenbringer moves to the front row, allowing melee classes to deal full damage. She'll forcefully regenerate her limbs if her HP reaches 50%, 40%, or 20%. There's also a hard hitting co-op attack she'll use if you leave the limbs alive for too long, so really take them out fast when she starts telegraphing it.

After you destroy the face, or rather massively dislocate her jaw (take a look at the Bared Essence's entry in the Monstrous Codex, and move the camera left or right...), you still need to kill the Bared Essence to finish the fight. You have 3 turns to deal damage to her before she regenerates Heavenbringer's face and hands. Fortunately the face only gets healed to 20% HP, so you don't have to redo the entire fight if that happens. You can delay her face closing by using a head bind, but this party doesn't have access to those. The Bared Essence takes 50% extra damage from everything, including Almighty damage, so go nuts with damage to finish the game.