How do Deathknell triggers work with the new cleanup step rules, and is there a contradiction between when Deathknell effects become pending (322.3) versus when they're described as activating (734.1.d)?

Ruling: Deathknell triggers when a unit is instructed to die, with the triggered ability going on the chain just before the unit actually goes to the trash. If the kill instruction is replaced or the death doesn't happen, the Deathknell trigger doesn't occur (per 734.1.d.1).

Sequence:

• Unit receives instruction that would kill it (active kill) or game sees unit is going to die (passive kill during cleanup)
• Deathknell trigger is put on the chain as a pending item
• Unit is then sent to the trash

Nuances:

• The process splits "dying" into two steps: receiving the kill instruction and actually going to the trash
• Both steps are part of the unit "dying" but Deathknells divide them to allow the trigger to go on the chain
• Active kills are covered by 415.1.a.1.b (kill instruction), while cleanup deaths are passive kills
• The principle is the same for both types of kills despite different rule references