Dextra, Master Rogue

{t}: Put a stealth counter on Dextra. Activate
only during your turn.
Dextra enters the battlefield with a stealth
counter on it. As long as Dextra has a stealth
counter, it has hexproof, can't be blocked, and:
{t}: Double Dextra's Power until end of turn,
then Dextra fights target creature you don't control.
Activate only as a sorcery.
After Dextra has dealt or received any damage,
remove all stealth counters from it.