Requires

Sigil of the New Dawn must be on the battlefield. Crystalline Crawler must be in hand. Doubling Season must be on the battlefield. Phyrexian Altar must be on the battlefield. Mana needed: in at least three different colors

Steps

1. Cast Crystalline Crawler giving it six +1/+1 counters because of Doubling Season.
2. Remove all six counters getting .
3. Sacrifice Crawler to Altar for one mana of any color.
4. Pay Sigil's cost of returning Crawler to hand.
5. Recast Crystalline Crawler for all but one of the remaining floating mana giving it eight +1/+1 counters.
6. Remove all eight counters netting of assorted colors containing at least .
7. Repeat steps 4-7.

Results