Pietro Maximoff, Quicksilver

Flash, first strike, haste
X-Trait --- Whenever you cast your second spell
of the turn, Pietro Maximoff, Quicksilver gains unblockable until end of turn.
Dash {r}{r} (You may cast this spell for its dash cost.
If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)