When Lightning Crafter enters the battlefield, its champion ability triggers.
Holding priority, activate Kiki-Jiki by tapping it, creating a token copy of Lightning Crafter with haste.
When the token Lightning Crafter enters the battlefield, its champion ability triggers, exiling Kiki-Jiki.
Activate the token Lightning Crafter by tapping it, dealing 3 damage to any target.
Activate Altar of Dementia by sacrificing the token Lightning Crafter.
When the token Lightning Crafter leaves the battlefield, it triggers, returning Kiki-Jiki from exile to the battlefield.
Resolve the Altar of Dementia ability.
Repeat from step 3.
This loop relies on an ingenious game of hide-and-seek fueled by Kiki-Jiki, Mirror Breaker and Lightning Crafter. By using Kiki-Jiki, Mirror Breaker to copy Lightning Crafter, the token’s entry trigger exiles Kiki-Jiki, Mirror Breaker to keep it safe from harm while setting up an infinite cycle. Before sacrificing the token to Altar of Dementia, you tap it to fling 3 damage at any target, letting Altar of Dementia grind through your opponent's library with mill triggers. Finally, sacrificing the token sends it to the graveyard, which triggers Lightning Crafter's return ability to bring Kiki-Jiki, Mirror Breaker back to the battlefield so the entire process can begin anew.