Cast Gatta and Luzzu by paying {2}{W}.
When Gatta and Luzzu enters the battlefield, it triggers, targeting Walking Ballista.
Activate Walking Ballista by removing a +1/+1 counter from it, targeting itself, but instead putting two +1/+1 counters on it due to Gatta and Luzzu and Hardened Scales.
Activate Walking Ballista by removing a +1/+1 counter from it, dealing 1 damage to any target.
Repeat from step 3.

Infinite damage

Infinite +1/+1 counters on a creature

Gatta and Luzzu

Hardened Scales

Walking Ballista

Cast Star of Extinction by paying {5}{R}{R}.
Holding priority, cast Gatta and Luzzu by paying {2}{W}.
When Gatta and Luzzu enters the battlefield, it triggers, targeting a creature you control.
Resolve Star of Extinction, destroying target land and dealing 20 damage to each creature and each planeswalker. The creature targeted by Gatta and Luzzu will not be dealt damage, and will instead have twenty +1/+1 counters put on it.
At the beginning of your next upkeep, Mayael's Aria triggers, causing you to put a +1/+1 counter on each creature you control, gain 10 life and win the game.

Win the game at the beginning of your next upkeep

Mayael's Aria

Star of Extinction

Cast Star of Extinction by paying {5}{R}{R}.
Holding priority, cast Gatta and Luzzu by paying {2}{W}.
When Gatta and Luzzu enters the battlefield, it triggers, targeting a creature you control.
Resolve Star of Extinction, destroying target land and dealing 20 damage to each creature and each planeswalker. The creature targeted by Gatta and Luzzu will not be dealt damage, and will instead have twenty +1/+1 counters put on it.
Simic Ascendancy triggers, putting twenty growth counters on it.
At the beginning of your next upkeep, Simic Ascendancy triggers, causing you to win the game.

Combos with "Gatta and Luzzu"