Basalt Monolith + Sydri, Galvanic Genius + Agatha of the Vile Cauldron

Basalt Monolith

Sydri, Galvanic Genius

Agatha of the Vile Cauldron

How it works

1. Activate Sydri's first ability by paying , causing Basalt Monolith to become a 3/3 artifact creature until end of turn.
2. Activate Basalt Monolith's first ability by tapping it, adding CCC.
3. activate Basalt Monolith's second ability by paying at most 2, untapping it.
4. Repeat from step 2.

This ingenious loop turns a classic mana rock into an infinite engine by transforming Basalt Monolith into a 3/3 artifact creature with Sydri, Galvanic Genius, setting its mana value to 3. Because Agatha of the Vile Cauldron reduces the cost of activated abilities of creatures you control by her power (which is 2), the cost to untap Basalt Monolith drops from {3} down to just {2}. Tapping the Monolith for three colorless mana and spending two to untap it leaves you with a net profit of one colorless mana each cycle, generating infinite colorless mana for commander, legacy, oathbreaker, and vintage play.