The Tenth Doctor + Reality Strobe + Agatha of the Vile Cauldron + Sol Ring

The Tenth Doctor

Reality Strobe

Agatha of the Vile Cauldron

Sol Ring

How it works

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