Scuttling Sliver + Trazyn the Infinite + Amoeboid Changeling + Grim Monolith

Scuttling Sliver

Trazyn the Infinite

Amoeboid Changeling

Grim Monolith

How it works

1. Activate Amoeboid Changeling by tapping it, causing Trazyn to become a Sliver until end of turn.
2. Activate Trazyn using Grim Monolith's ability by tapping it, adding CCC
3. Activate Trazyn by paying 2, untapping it.
4. Repeat from step 2.

This clever graveyard-and-battlefield synergy hinges on turning Trazyn the Infinite into a Sliver so it can borrow the untap ability granted by Scuttling Sliver to your team. Once Trazyn has that ability, it also inherits Grim Monolith's activated abilities from the graveyard through Prismatic Gallery, letting it tap for three colorless mana at the cost of a mere two-mana untap. To pull this off, you first need to use Amoeboid Changeling to give Trazyn the necessary creature types, bridging the gap between your graveyard's artifacts and your battlefield's Slivers. The result is a self-sustaining mana engine that generates infinite colorless mana, allowing you to flood the board and overwhelm your opponents.