Hidden Ancients 
Enchantment
When an opponent casts an enchantment spell, if this permanent is an enchantment, it becomes a 5/5 Treefolk creature.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL
Enchantment
When an opponent casts an enchantment spell, if this permanent is an enchantment, it becomes a 5/5 Treefolk creature.