Agatha of the Vile Cauldron + Silvanus's Invoker + High Tide

Agatha of the Vile Cauldron

Silvanus's Invoker

High Tide

How it works

1. Cast High Tide by paying .
2. Activate an Island by tapping it, adding .
3. High Tide triggers, adding .
4. Activate Silvanus's Invoker by paying 1, untapping the land and causing it to become an 8/8 Elemental with trample and haste in addition to its other types until end of turn.
5. Repeat from step 2

This loop transforms your mana base into a devastating engine by heavily discounting activated abilities with Agatha of the Vile Cauldron, making Silvanus's Invoker cost just {1} to activate. Because High Tide supercharges your Islands to yield double blue mana every time they are tapped, a single land can easily pay for the Invoker's ability while leaving extra mana left over. Repeating this process lets you infinitely untap your lands for massive amounts of mana, setting up a lethal board state in formats like commander, legacy, and vintage.