Prowling Geistcatcher + Kiki-Jiki, Mirror Breaker + Phyrexian Altar

Prowling Geistcatcher

Kiki-Jiki, Mirror Breaker

Phyrexian Altar

How it works

1. Activate Kiki-Jiki by tapping it, creating a token copy of Prowling Geistcatcher with haste.
2. Activate Phyrexian Altar by sacrificing Kiki-Jiki, adding one mana of any color.
3. When Kiki-Jiki dies, the nontoken and token Prowling Geistcatcher's first abilities trigger.
4. Resolve the token Prowling Geistcatcher's trigger, exiling Kiki-Jiki from your graveyard.
5. Resolve the nontoken Prowling Geistcatcher's trigger, doing nothing.
6. Activate Phyrexian Altar by sacrificing the Prowling Geistcatcher token, adding one mana of any color.
7. When the token Prowling Geistcatcher dies, its second ability and the nontoken Prowling Geistcatcher's first ability triggers.
8. Resolve the nontoken Prowling Geistcatcher trigger, putting a +1/+1 counter on it.
9. Resolve the token Prowling Geistcatcher trigger, returning Kiki-Jiki from exile to the battlefield.
10. Repeat.

This clever loop sets up an endless cycle of sacrifice and rebirth by using Phyrexian Altar as both your mana source and your way to send creatures to the graveyard. When Kiki-Jiki, Mirror Breaker makes a copy of Prowling Geistcatcher, sacrificing Kiki-Jiki to the Altar triggers the Geistcatcher's exile ability while leaving behind a trail of returning cards. Because Prowling Geistcatcher's own death triggers a cascade that brings Kiki-Jiki right back to the battlefield, you can endlessly regenerate your engine, netting infinite mana, endless death triggers, and a growing mountain of +1/+1 counters.