If Irelia, Fervent has Guardian Angel equipped and the opponent plays Imperial Decree, then attacks with two 6 might units, does Irelia die or survive at the end of combat?

Ruling: Irelia will be saved by Guardian Angel and survive. Imperial Decree triggers when Irelia takes any amount of damage and creates a "kill" effect, but Guardian Angel acts as a replacement effect that prevents the death, destroying itself instead and recalling Irelia to base.

Sequence:

• Imperial Decree resolves and becomes active
• Combat damage is dealt to Irelia (all opposing might added together and dealt at once)
• Imperial Decree trigger is placed on the chain because Irelia took non-zero damage
• Imperial Decree trigger resolves, attempting to kill Irelia
• Guardian Angel triggers as a replacement effect, preventing the death
• Guardian Angel is destroyed, Irelia is healed, exhausted, and recalled to base

Nuances:

• Imperial Decree triggers on any amount of damage taken, not just lethal damage
• Guardian Angel works as a replacement effect that intercepts the "die" event from Imperial Decree
• If Irelia is buffed to survive the combat damage (e.g., 15 might), the sequence is the same - Imperial Decree still triggers from the non-lethal damage, but Guardian Angel still saves her
• Combat damage from multiple units is added together and dealt as a single instance