Thryx, the Sudden Storm 
Legendary Creature — Elemental Giant
Flash (You may cast this spell any time you could cast an instant.)
Flying
Spells you cast with mana value 5 or greater cost 
less to cast and can't be countered.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL