When Survey Mechan dies, Mortuary triggers, putting Survey Mechan from your graveyard onto the top of your library.
Teval triggers, creating two creature tokens.
Resolve the Survey Mechan ability, dealing 3 damage to any target and causing you to draw three cards and gain 3 life.
Activate Ashnod's Altar twice by sacrificing the two creature tokens, adding CCCC.
Cast Survey Mechan by paying 4.
Repeat.
This ingenious loop turns Survey Mechan into a self-sustaining engine by utilizing Mortuary to constantly recycle it straight to the top of your library for recasting. While Ashnod's Altar provides the colorless mana to recast Survey Mechan, Teval, the Balanced Scale acts as the vital bridge, producing a Zombie Druid token whenever Survey Mechan leaves the graveyard. To supercharge this token generation, Elspeth, Storm Slayer steps in as a doubler to ensure that Teval yields a surplus of sacrifice fodder—turning each iteration into an infinite cascade of card draw, life, and damage.