If a unit controlled by Sett dies from Imperial Decree with enough damage to normally kill it, does it die twice (once from damage and once from the Decree trigger), bypassing Sett's save?

Ruling: Yes, if a unit takes lethal damage and Imperial Decree triggers, it dies twice - once from damage equaling might and once when the Imperial Decree trigger resolves - which bypasses one-time save effects like Sett's legend ability.

Sequence:

• Unit takes damage from Imperial Decree
• Imperial Decree trigger goes on the chain
• In cleanup, the unit would die from damage equaling might and Sett saves it
• The Imperial Decree trigger is finalized in the same cleanup
• When the Imperial Decree trigger resolves, the unit is killed again

Nuances:

• If the unit takes non-lethal damage (e.g. 1 damage but has more than 1 might), it only dies once from the Imperial Decree trigger and Sett can save it
• To kill through one-time replacement effects like Sett or Zhonya's, you need to kill the unit in two stages: either make them die to damage AND the Imperial Decree trigger, or make them die to two Imperial Decree triggers (e.g. Imperial Decree into Falling Star creates two separate Imperial Decree triggers)