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.
Random a card of Magic: The Gathering (MTG), but you can also roll the D20 dice, random a Planeswalker, have fun with the random rules and more.