Persist Creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it and at least one +1/+1 counter on it due to
Metallic Mimic.
Remove a -1/-1 counter and a +1/+1 counter from that creature as a state-based action.
Resolve the
Grimgrin ability.
Repeat.
Results
Infinite +1/+1 counters on a creature.
Infinite creature ETB.
Infinite creature LTB.
Infinite creature sacrifice triggers.
Infinite death triggers.
Metadata
Bracket tag
OddballBracket 2-3+
Probably 2 or 3, but hard to classify
1
2
3
4
5
1 · Exhibition5 · cEDH
Bracket tags are estimated from the cards and results of each combo, as a guideline rather than a strict classification.