Activate the creature with Elemental Mastery attached by tapping it, creating a number of 1/1 Elemental creature tokens with haste equal to its power.
Activate Shilgengar by sacrificing an Elemental.
When the Elemental dies as an artifact due to Mycosynth Lattice, Dross Scorpion triggers, untapping the creature with Elemental Mastery attached.
Resolve the Shilgengar ability.
Repeat.
This intricate engine lets you spin up an endless horde of hasty attackers by converting your creatures into raw material and back again. Shilgengar, Sire of Famine provides the necessary sacrifice outlet to fuel the loop, transforming your casualties into Blood tokens while your enchanted creature—boosted by Elemental Mastery—continuously replenishes the board with fresh bodies. The secret glue holding this entire mechanical ecosystem together is Mycosynth Lattice, which turns every single permanent into an artifact, ensuring that whenever your token creatures die, Dross Scorpion's triggered ability fires to untap your token generator. This allows you to immediately repeat the process, turning an ordinary sacrifice loop into an unstoppable chain of production.