Kaydro, Mad after Mutation

Emerge as flash {x}{x}{x} — This enters the
battlefield with 2*X +1/+1 counters. You
can put any of the counters from sacrificed
creature on this.
ETB — Gain 2*X life. You can move up to
any 2*X counters from any targets to this,
then this fights with target creature you
don't control.