the dreamer's demon destroys an ongoing card when destroyed, while chronoranger's bounty destroys a 4hp target when its target leaves play. I put the bounty on the demon.
I considered "leave play" as a broader but simultaneous version of "destroyed", but I wanted to check my interpretation was correct:
1. I reduce the illusionary demon to 0 hp
2. the demon destroys the ongoing bounty and simultaneously the bounty destroys a different, 4hp projection
Alternatively:
1. I reduce the illusionary demon to 0 hp
2. the demon destroys the ongoing bounty while destroyed but before leaving play, hence the bounty does nothing