When Survey Mechan dies, Mortuary triggers, putting Survey Mechan from your graveyard onto the top of your library.
Chalk Outline triggers, creating two creature tokens and two Clue 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 loop transforms Survey Mechan into a self-sustaining engine by exploiting Ashnod's Altar to easily fund its recast cost, while Mortuary neatly recycles it straight back to the top of your library to draw again. Meanwhile, Chalk Outline turns Survey Mechan leaving the graveyard into a steady influx of material, which Elspeth, Storm Slayer doubles to ensure you always have enough sacrifice fodder for the Altar.