At the beginning of your upkeep, Mayael's Aria triggers.
Activate Mossbridge Troll by tapping creatures you control with a total power of ten or greater, giving Mossbridge Troll +20/+20.
Resolve the Mayael's Aria trigger, winning the game.

Win the game at the beginning of your next upkeep

Mayael's Aria

Mossbridge Troll

Activate Mossbridge Troll by tapping any other creatures you control except Sovereign Okinec Ahau with total power 10 or greater, giving Mossbridge Troll +20/+20 until end of turn.
Declare Sovereign Okinec Ahau as an attacker.
Sovereign Okinec Ahau triggers, putting twenty +1/+1 counters on Mossbridge Troll.
Simic Ascendancy's first ability triggers, putting 20 growth counters on it.
At the beginning of your next upkeep, Simic Ascendancy's second ability triggers, causing you to win the game.

Combos with "Mossbridge Troll"