The Tenth Doctor + Mana Echoes + Cyclical Evolution + Metallurgic Summonings

The Tenth Doctor

Mana Echoes

Cyclical Evolution

Metallurgic Summonings

How it works

1. Activate The Tenth Doctor by paying 7, removing all time counters from Cyclical Evolution.
2. Cyclical Evolution triggers, causing you to cast it from exile without paying its mana cost.
3. Metallurgic Summonings triggers, creating a creature token.
4. When the creature token enters, Mana Echoes triggers, adding C for each creature you control that shares a creature type with the token.
5. Resolve Cyclical Evolution.
6. Repeat.

This loop relies on accelerating suspended spells with The Tenth Doctor's time-travel activation to repeatedly cast Cyclical Evolution for free. Each time you cast it, Metallurgic Summonings triggers to create a Construct token, which in turn causes Mana Echoes to generate a growing surplus of colorless mana based on your shared creature types. You can funnel that newly generated mana right back into The Tenth Doctor's ability to strip the time counters off Cyclical Evolution, sending it back to the stack to repeat the process indefinitely for an arbitrarily large army and infinite mana.