{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.
The effect of Vorel's ability will essentially double the counters on the target artifact, creature, or land. For example, if a creature has three +1/+1 counters and a divinity counter on it before the ability resolves, it will have six +1/+1 counters and two divinity counters on it after the ability resolves.