Prowling Geistcatcher + Kiki-Jiki, Mirror Breaker + Altar of Dementia Combo

All permanents on the battlefield.

Activate Kiki-Jiki by tapping it, creating a token copy of Prowling Geistcatcher with haste.

Activate Altar of Dementia by sacrificing Kiki-Jiki.

When Kiki-Jiki dies, the nontoken and token Prowling Geistcatcher's first abilities trigger.

Resolve the token Prowling Geistcatcher's trigger, exiling Kiki-Jiki from your graveyard.

Resolve the nontoken Prowling Geistcatcher's trigger, doing nothing.

Resolve the Altar of Dementia ability, causing target player to mill cards equal to Kiki-Jiki's power.

Activate Altar of Dementia by sacrificing the Prowling Geistcatcher token.

When the token Prowling Geistcatcher dies, its second ability and the nontoken Prowling Geistcatcher's first ability triggers.

Resolve the nontoken Prowling Geistcatcher trigger, putting a +1/+1 counter on it.

Resolve the token Prowling Geistcatcher trigger, returning Kiki-Jiki from exile to the battlefield.

Resolve the Altar of Dementia ability, causing target player to mill cards equal to the token Prowling Geistcatcher's power.

Repeat.

Infinite +1/+1 counters on a creature

Infinite death triggers

Infinite creature ETB

Infinite creature LTB

Infinite mill

Infinite creature sacrifice triggers

Infinite self-mill