Valstrax, Argent Comet

Haste, Flying, First Strike

Exhaust—{x}{r}{r}: This creature does X damage
to any target, put a +1/+1 counter on Valstrax. (Activate each Exhaust ability only once.)

Partner with Mary, Valstrax Rider (When this creature enters the battlefield, target player may put Mary, Valstrax Rider into their hand from their library, then shuffle.)