Talk:Yorick/Strategy/@comment-186.57.149.197-20110705193258/@comment-98.119.154.25-20110709221900

The 50% applies to the dmg done when it is cast on the enemy champion. The lifesteal the ghoul gives you is 100% of the dmg it deals to the enemy. Which in turn is equal to only 30% of Yorick's total damage.

Therefore, the ghoul on cast/summon dmg is 50% of the abilities described amount when you hover over the skill in game, and it deals 30% of Yoricks damage giving 100% lifesteal from that.