Cayth, Famed Mechanist + Mana Echoes + Umbral Mantle

Cayth, Famed Mechanist

Mana Echoes

Umbral Mantle

How it works

1. Activate Cayth by paying 2 and tapping it, creating a token copy of a creature token you control.
2. When the creature token enters the battlefield, Mana Echoes triggers, adding C for each creature you control that shares a creature type with it.
3. Activate Cayth by paying 3 and untapping it, giving it +2/+2 until end of turn.
4. Repeat.

This fascinating loop transforms Cayth, Famed Mechanist into a self-sustaining engine by taking advantage of the creature tokens it creates. Whenever you pay to activate Cayth's ability to populate, the new token entering the battlefield triggers Mana Echoes, showering you with colorless mana based on your shared creature types. You then funnel that generated mana straight into Umbral Mantle to untap Cayth and pump its power. Because Umbral Mantle costs zero to re-equip if needed and Cayth's untap ability only demands {3} and {Q}, you can repeat this cycle endlessly to flood the board with infinite creature tokens, accumulate infinite mana, and proliferate to your heart's content.