({6} magic symbol) plus six ({G} magic symbol) available.
Steps
At the beginning of your upkeep,
Mayael's Aria triggers.
Holding priority, activate
Chameleon Colossus by paying ({2} magic symbol) ({G} magic symbol) ({G} magic symbol) , causing it to get +X/+X until end of turn, where X is its power.
Repeat step 2 until
Chameleon Colossus has power 20 or greater.
Resolve the
Mayael's Aria trigger, causing you to put a +1/+1 counter on each creature you control, gain 10 life and win the game.
Notes
The mana prerequisite assumes
Chameleon Colossus has 4 power when executing the combo. If it has more power, the mana cost will be reduced accordingly.