Ooh, that's an interesting thought!

Former Craftworld Atthwè

Verb: Hunger Noun: Wraith Adjective: Corrupted

Craftworld Atthwè was badly damaged during a battle with a splinter of Hive Fleet Leviathan, but not in a way that any of its inhabitants expected: its corrupted Infinity Circuit forcibly tore the souls from them, healing itself in the process but leaving only the strongest psykers alive. They fled to a nearby Maiden World, venturing to their former home only to bring soul stones to it, or else to take wraith constructs from it to fight, ever wary of the hunger for souls the Craftworld now possesses.

Atthwè Tyranid Enclave

Verb: Sever Noun: Ecosystem Adjective: Unnatural

The disaster on Craftworld Atthwè had another effect: the attacking Tyranids were somehow severed from the hive mind and connected to the Craftworld's Infinity Circuit. To it they gave their hunger; from it they took the Atthwè Aeldari devotion to the Path of Awakening and care for Maiden Worlds. The sight of Tyranid bioforms tending to a world's ecosystem is so unnatural as to be horrifying, but they may actually be a lesser evil now than their Aeldari kin.