Time Wizard

At the start of your upkeep, gain 1 reroll token.
(It’s an artifact with {t}, sacrifice this artifact: Reroll 1 die before calculating the result)
{t}, Target a spell, activated ability, or triggered ability on the stack: Roll a d6
• 1 - 3 | Copy targeted spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)
• 4 - 6 | Counter targeted spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)