6-Legged Xenomorph

Haste, Trample, Menace
{x}{b}{b}: Monstrosity X (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)
When 6-Legged Xenomorph becomes monstrous, if X was 6 or more, it gains Vigilance.
As long as 6-Legged Xenomorph is monstrous, it gains a +1/+1 counter whenever it deals damage to another creature.