If Aria of Flame leaves the battlefield while its last ability is on the stack, use the number of verse counters it had on it immediately before it left the battlefield to determine how much damage it deals.

Aria of Flame’s last ability resolves before the spell that caused it to trigger. It resolves even if that spell is countered.

In a Two-Headed Giant game, Aria of Flame’s first ability causes the opposing team to gain 20 life.

If the target player or planeswalker is an illegal target by the time Aria of Flame’s last ability tries to resolve, the ability doesn’t resolve. You don’t put a verse counter on Aria of Flame.