Hidden Guerrillas 
Enchantment
When an opponent casts an artifact spell, if this permanent is an enchantment, it becomes a 5/3 Soldier creature with trample.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL