[Endoperez]

Vanilla Dom3 has two enslavement weapons:
274 Enslave Mind
189 Enslavement

and several life-draining weapons, including:
63 Life Drain
449 Life Drain
271 Life Drain Tentacle

I still haven't tried this out, but here's my two cents re: Pirians.
There are several Astral spells they should be able to cast. Solar Brilliance, Light of the Northern Star, Astral Fires... Some of the spells could be made national-only, others could have different versions that the Pirians could cast, if you don't want to give them much astral.

Fire/Water spells could also work well. Acid Storm to destroy all armor on the battlefield would be pretty evil.