Commander Masters

Endrek Sahr, Master Breeder

Whenever you cast a creature spell, create X 1/1 black Thrull creature tokens, where X is that spell's mana value.
When you control seven or more Thrulls, sacrifice Endrek Sahr, Master Breeder.

The List

Modern Masters 2015

Whenever you cast a creature spell, put X 1/1 black Thrull creature tokens onto the battlefield, where X is that spell's converted mana cost.
When you control seven or more Thrulls, sacrifice Endrek Sahr, Master Breeder.

Commander 2013

Time Spiral

Whenever you play a creature spell, put X 1/1 black Thrull creature tokens into play, where X is that spell's converted mana cost.
When you control seven or more Thrulls, sacrifice Endrek Sahr, Master Breeder.