At the beginning of your upkeep, Mayael's Aria triggers.
Holding priority, cast Aura Mutation by paying , destroying target enchantment with mana value five or greater, and creating at least five 1/1 Warrior creature tokens.
When the Warriors enter the battlefield, Devilish Valet triggers that many times, doubling its power that many times, causing its power to be at least 32 until end of turn.
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.
This explosive combination turns a well-timed instant into an instant-win condition by rapidly scaling creature power through exponential growth. During your upkeep, you use Aura Mutation to destroy a pricey enchantment and flood the board with Saproling tokens, which triggers Devilish Valet’s alliance ability over and over to skyrocket its power far past the threshold you need. This leaves Devilish Valet with a massive power of 32 or greater just in time for Mayael's Aria to resolve its upkeep trigger, effortlessly checking off the requirement to win the game.