Magosi, the Waterveil (Zendikar)
Found the breaking combo! It's four cards, and breaks into extended, but only two colors.
First, of course, you need this card. You also need a white and blue mana source, and two more, potentially colorless. Once you have this card in play, you need to untap it: Unbender Tine. Then you activate for an eon counter, using your blue mana source. Then you untap it with a second Unbender Tine. Then you activate the last ability, doubling it with Rings of Brighthearth.
I'm looking for a better way of doing this, but Rings and Unbender are pretty good on their own, and you can skip the first untap if you aren't worried about an *infinite* number of turns (or if you have another Magosi in your hand).
