Tainted Observer + Mana Echoes + Scurry Oak

Tainted Observer

Mana Echoes

Scurry Oak

How it works

1. Cause a creature to enter the battlefield under your control.
2. When the creature enters the battlefield, Tainted Observer and Mana Echoes triggers.
3. Resolve the Mana Echoes trigger, adding C for each creature that shares a creature type with the creature that entered the battlefield.
4. Resolve the Tainted Observer trigger, causing you to pay 2 to put a +1/+1 counter on Scurry Oak.
5. Scurry Oak triggers, creating a 1/1 Squirrel creature token.
6. Repeat from step 2.

This clever loop is fueled by Mana Echoes, which generates an escalating flood of colorless mana every time a creature enters the battlefield by counting all sharing types. Scurry Oak acts as the central engine, using its evolve ability to start the chain and then spinning off fresh Squirrel tokens every time counters land on it. Meanwhile, Tainted Observer oversees the operation, letting you spend a portion of that mana to proliferate—or simply turning every new token into another cycle of triggers. Together, these three pieces feed into one another indefinitely, filling your board with an endless army while boosting your creatures to astronomical proportions.