Survey Mechan + Mortuary + Ashnod's Altar + Skeleton Crew + Elspeth, Storm Slayer

Survey Mechan

Mortuary

Ashnod's Altar

Skeleton Crew

Elspeth, Storm Slayer

How it works

1. Activate Survey Mechan by sacrificing it.
2. When Survey Mechan dies, Mortuary triggers, putting Survey Mechan from your graveyard onto the top of your library.
3. Skeleton Crew triggers, creating two creature tokens.
4. Resolve the Survey Mechan ability, dealing 3 damage to any target and causing you to draw three cards and gain 3 life.
5. Activate Ashnod's Altar twice by sacrificing the two creature tokens, adding CCCC.
6. Cast Survey Mechan by paying 4.
7. Repeat.

This loop relies on Survey Mechan as the expendable engine, dropping its steep activation cost to a manageable four mana thanks to lands, and sacrificing it to Ashnod's Altar to recoup that exact mana while sending the artifact creature to the graveyard. The moment Survey Mechan dies, Mortuary immediately tucks it safely back onto the top of your library, while Skeleton Crew catches the creature leaving the graveyard to trigger token creation. Because Elspeth, Storm Slayer doubles every token generated, that single graveyard departure yields two creature tokens instead of one, which can then be sacrificed right back to Ashnod's Altar for four mana to recast Survey Mechan and draw it right back into your hand.