The Tenth Doctor + Reality Strobe + Agatha of the Vile Cauldron + Electro, Assaulting Battery

The Tenth Doctor

Reality Strobe

Agatha of the Vile Cauldron

Electro, Assaulting Battery

How it works

1. Cast the noncreature permanent by paying 0.
2. Activate The Tenth Doctor by paying at most 1, removing three time counters from Reality Strobe.
3. Reality Strobe triggers, causing you to cast it from exile without paying its mana cost.
4. Electro triggers, adding .
5. Resolve Reality Strobe, returning Mana Vault from the battlefield to your hand, and then exiling Reality Strobe with three time counters on it.
6. Repeat.

This intricate loop relies on Agatha of the Vile Cauldron to slash the activation cost of The Tenth Doctor's Timey-Wimey ability down to just a single generic mana. With that discount in place, you can continually manipulate time counters to rapidly strip them from Reality Strobe, forcing it to cast itself for free over and over again. As you cast this spell repeatedly, Electro, Assaulting Battery generates a steady stream of red mana while ensuring your unspent mana never drains away between steps and phases.