Neelix

Whenever you cast a white, blue, red, or green spell, Neelix gets +1/+1 until end of turn and you gain 1 life.
Whenever an opponent casts a black spell, Neelix gets +1/+1 until end of turn and you gain 1 life.
"Without a doubt, he's the most versatile member of our crew."
- Chakotay