Mendicant Core, Guidelight + Ashnod's Altar + Workshop Assistant

Mendicant Core, Guidelight

Ashnod's Altar

Workshop Assistant

How it works

1. Cast Workshop Assistant by paying 3.
2. Mendicant Core triggers, causing you to pay 1 to copy the Workshop Assistant spell, creating a token copy of it.
3. Activate Ashnod's Altar by sacrificing the nontoken Workshop Assistant, adding CC.
4. When Workshop Assistant dies, it triggers, returning another artifact from your graveyard to your hand.
5. Activate Ashnod's Altar by sacrificing the token Workshop Assistant, adding CC.
6. When the token Workshop Assistant dies, it triggers, returning the nontoken Workshop Assistant from your graveyard to your hand.
7. Repeat.

This engine relies on Mendicant Core reaching max speed to let you pay {1} and copy any artifact spell you cast, turning a single Workshop Assistant into both a permanent and a token copy. Ashnod's Altar then provides the mana needed to pay for Mendicant Core's duplication ability while turning your looping mechanical assistants into a continuous stream of sacrifices. As you cycle Workshop Assistant back and forth between the battlefield and the graveyard, its triggered ability constantly returns whichever artifact you need right back to your hand.