Basalt Monolith + Xenic Poltergeist + Training Grounds

Basalt Monolith

Xenic Poltergeist

Training Grounds

How it works

1. Activate Xenic Poltergeist by tapping it, causing Basalt Monolith to become an artifact creature until end of turn.
2. Activate Basalt Monolith's first ability by tapping it, adding CCC.
3. Activate Basalt Monolith's last ability by paying 1, untapping it.
4. Repeat from step 2.

This clever loop turns a heavy-duty mana rock into a self-sustaining engine by temporarily animating it. Xenic Poltergeist does the heavy lifting of turning Basalt Monolith into an artifact creature, which is essential because Training Grounds only reduces the cost of activated abilities belonging to creatures. With Training Grounds on the board discount-wise, the cost to untap Basalt Monolith drops from three mana down to just one, allowing you to tap it for three colorless mana, spend one to untap it, and net infinite colorless mana in the process.