Elite Arcanist + Chakram Retriever + Pact of the Titan + Warstorm Surge

Elite Arcanist

Chakram Retriever

Pact of the Titan

Warstorm Surge

How it works

1. Activate Elite Arcanist by paying 0 and tapping it, casting a copy of Pact of the Titan without paying its mana cost.
2. Chakram Retriever triggers, untapping Elite Arcanist.
3. Resolve Pact of the Titan, creating a 4/4 Giant creature token.When the Giant enters the battlefield, Warstorm Surge triggers, dealing damage equal to the Giant's power to any target.
4. Repeat.

By exiling Pact of the Titan with Elite Arcanist, you gain the ability to repeatedly cast it for free by paying zero into its {X} activation cost. Every time you cast that spell on your turn, Chakram Retriever's triggered ability untaps Elite Arcanist so you can immediately repeat the process. Meanwhile, the resulting flood of creatures causes Warstorm Surge to rain down infinite damage equal to their power on any target of your choice.