Gargos, Vicious Watcher 
Legendary Creature — Hydra
Vigilance
Hydra spells you cast cost 
less to cast.
Whenever a creature you control becomes the target of a spell, Gargos fights up to one target creature you don't control.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL