Fox the betrayer

Vigilance, deathtouch, first strike.
When Fox the betrayer enters the battlefield, you
may sacrifice {x} creatures you control. For every creatures sacrificed this way :
deal {x} damages to any player and any player sacrifice {x} creatures.
If {x} is more than 4, Fox the betrayer power
and toughness become 30, gains haste et trample.
Behind his charismatic appearance lies a terrible schemer drunk on power and fame.