Silvanus's Invoker + Guildless Commons + Agatha of the Vile Cauldron

Silvanus's Invoker

Guildless Commons

Agatha of the Vile Cauldron

How it works

1. Activate Guildless Commons by tapping it, adding CC.
2. Activate Silvanus's Invoker by paying 1, untapping Guildless Commons and causing it to become an 8/8 Elemental with trample and haste in addition to its other types until end of turn.
3. Repeat.
4. Once you have infinite mana, you may tap and untap any other land(s) you control, and if you control lands that can produce and , use the mana to activate Agatha of the Vile Cauldron's ability.

This loop relies on Guildless Commons tapping for two colorless mana while Agatha of the Vile Cauldron's power reduces the activation cost of Silvanus's Invoker down to just a single mana. By channeling that generated mana back into the Invoker, you repeatedly untap Guildless Commons to generate an infinite surplus of colorless mana. Because the Invoker also animates the land into a massive threat, you can simultaneously produce an arbitrarily large creature while cycling other lands to pump your entire board through Agatha's team-buff ability.