Tattermunge Duo 

Creature — Goblin Warrior Shaman
Whenever you cast a red spell, this creature gets +1/+1 until end of turn. Whenever you cast a green spell, this creature gains forestwalk until end of turn. (It can't be blocked as long as defending player controls a Forest.)
Legality
standardNOT LEGALpioneerNOT LEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL