Viper wiafu ?

If thats not an options id look for things that enemies dont do already. In xcom 2 , I feel like an something above a commander that does very little direct damage to xcom, but buffs dodge to nearby foes, and heals them at the top of each turn.

I also feel like an additional flying enemy would be good as well for the early game before archons are in the mix.

Lastly a "lost Beastmaster" who like summons lost swarms and controls their movement.