Vigorclaw Sentinel

Fluctuate (You cannot pay this spell's {x} cost. As
you cast this spell, roll a six-sided die.This spell's {x} cost value becomes the result.)
Vigorclaw Sentinel enters the battlefield with X +1/+1 counters on it.
As long as Vigorclaw Sentinel has 5 or less +1/+1 counters on it, it has "{t}: Put a +1/+1 counter on this creature".