Claws of Kokytos, how to defeat it.

[Aleph]

I've used it in conjunction with Astral Corruption to continue to cast large non-Blood spells. I can tell you that the Doom Horrors survive just fine, and will eventually escape to wreak havoc elsewhere, although it's quite a different thing to have a permanent Doom Horror on the map than a temporary Doom Horror trying to assassinate your caster.

[LoloMo]

Wait a minute here, the assassin horror unit becomes a permanent unit after being sent to Kokytos? Interesting!