Goblin Tinkerer

When Goblin Tinkerer enters, he is applied to a chosen creature you control.

{t}, Roll a six sided die. If you roll a 3 or below, the enchanted creature is given a minus X/X modifier where X is the number you rolled. If you roll a 4 or above, the enchanted creature is given a plus X/X modifier where X is the number you rolled. This number can be re-rolled as long as the enchantment is untapped.