AnyIncreases +1/+1 Counter Placement but not -1/-1
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How it works
Prerequisites
At least one persist creature has a +1/+1 counter on it.
2x Persist Creature; Increases +1/+1 Counter Placement but not -1/-1
Steps
1Activate Altar of Dementia by sacrificing the persist creature that has a +1/+1 counter on it.
2When that creature dies, its persist ability and Host of the Hereafter trigger.
3Resolve Host of the Hereafter's ability, putting at least two +1/+1 counters onto the surviving persist creature due to the counter-increasing effect.
4If that creature had a -1/-1 counter on it, remove that and one of the +1/+1 counters from it as a state-based action.
5Resolve the persist ability from step 2, returning the persist creature from your graveyard to the battlefield with a -1/-1 counter.
6Resolve the Altar of Dementia ability from step 1.