Beckoning The Sovereign Death

As an additional cost to cast this spell, sacrifice
any number of creatures.

This enchantment enters with X +1/+1 counters.
Create a number of 1/1 black skeleton creature
tokens equal to the number of creatures sacrificed
plus one.

At the beginning of your end step, you may remove
any number of +1/+1 counters from this enchantment
and put them onto a skeleton you control.