Cheapest priced copy (Unfinity): $0.35 at Card Kingdom, near mint, their price list as of .
Monitor Monitor 
Creature — Human Employee · 2/5 · Uncommon · Unfinity · #52
When this creature enters, open an Attraction. (Put the top card of your Attraction deck onto the battlefield.)
Once each turn, you may pay {1} to reroll one or more dice you rolled.
Legal inCommander
Banned inLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
2 printings · $0.35 to $6.99 at Card Kingdom
4 rulings from Wizards of the Coast
- 7 October 2022If you roll multiple dice at the same time, paying {1} will let you reroll any number of those dice. You don’t have to pay {1} per die.
- 7 October 2022If you control multiple Monitor Monitors, you may use each of them once each turn. You may use multiple Monitor Monitors on the same die roll if you wish.
- 7 October 2022You decide whether to use Monitor Monitor’s ability right after you monitor the result of the die roll. You can’t wait and use it to reroll that die later.
- 7 October 2022You can use Monitor Monitor’s reroll ability on any die roll, including a roll of the planar die in a Planechase game.