Chimichanga's Assassin

If {x} is one, it is a 1/1 creature.
If {x} is two, it is a 1/1 creature with deathtouch.
If {x} is three, it is a 2/2 creature with flying.
If {x} is four, it is a 3/3 creature with trample.
If {x} is five, it is a 3/3 creature with firststrike.
If {x} is six or more, it is a 4/4 creature with "All creatures you own have vigilance"