I had an idea for a homebrew magic item - at least, I *think* it's homebrew as I can't find anything similar online; but I was *sure* the Critical Role crew have something similar...

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> Stone of Luck
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> Once per day, you may activate this stone targeting one creature you can touch. For the next hour, that creature may reroll one Ability Check, Attack Roll or Saving Throw of their choice (they must use the new roll).
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What rarity would you assign to this? I think (I'm hoping) it feels Uncommon, but I'm really not sure.