Dross Scorpion + Elemental Mastery + Biotransference + Yahenni, Undying Partisan

Dross Scorpion

Elemental Mastery

Biotransference

Yahenni, Undying Partisan

How it works

1. 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.
2. Activate Yahenni by sacrificing an Elemental.
3. When the Elemental dies as an artifact due to Biotransference, Dross Scorpion triggers, untapping the creature with Elemental Mastery attached.
4. Resolve the Yahenni ability.
5. Repeat.

This loop hinges on Biotransference to bridge the gap between your creatures and Dross Scorpion's artifact-untapping wrath, turning every death into a mechanical catalyst. When you tap the creature enchanted by Elemental Mastery, it spits out a horde of tokens that Biotransference immediately imbues with the artifact type. Sacrificing one of those tokens to Yahenni, Undying Partisan triggers the Scorpion to untap your engine creature, letting you repeat the cycle indefinitely.