Arbs, Master of All

When Arbs, Master of All enters the battlefield
you destroy all creatures opponents control.
You gain life equal to their toughness and
opponents lose life equal to their power.
Sleepy Times—When you gain life you may pay {1}{g} if you do double the life gained.
{x}—Put x sleep counters on Arbs, Master of all.
When you have 15 sleep counters you win.