Gilder Bairn + Crystalline Crawler + A Realm Reborn

Gilder Bairn

Crystalline Crawler

A Realm Reborn

How it works

1. Activate A Realm Reborn by tapping Gilder Bairn, adding one mana.
2. Activate Gilder Bairn by paying 2G/U and untapping it, doubling each counter on Crystalline Crawler.
3. Activate Crystalline Crawler as many times as necessary by removing counters from it, adding at least two mana.
4. Repeat from step 2.
5. Once you have infinite counters on Crystalline Crawler, you may instead double the counters on any other permanents.