Xenomorph Queen

{t} Place an egg token on the field with the effect: "Sacrifice token to destroy target creature, put a 4/4 Alien token on the field."
{t}{5}Sacrifice this creature. Summon a xenomorph queen egg with 3 counters on it. When a Xenomorph dies, remove or add a counter. When it reaches 0, it becomes a xenomorph queen with X +1/+1 counters on it, where X is the power of the last xenomorph queen.