Infinite +1/+1 counters on a creatureInfinite death triggersInfinite creature ETBInfinite creature LTBInfinite creature sacrifice triggers
How it works
Activate Bloodflow Connoisseur by sacrificing Moritte of the Frost.
When Moritte of the Frost dies, it triggers its persist ability, returning itself to the battlefield as a copy of the creature with persist with two +1/+1 counters and one -1/-1 counter on it.
Remove one +1/+1 counter and one -1/-1 counter from Moritte of the Frost as a state-based action.
Resolve the activated ability from step 1, putting a +1/+1 counter on Bloodflow Connoissuer.