Fenghuang's ability sais: 'When dying instead return to owner's hand...'
So, logically, the creature doesn't die.
It also doesnt work with soul catcher, graveyard, etc...
Also, time bomb should return at full health: it dealt damage to itself, but it didn't lower its max hp.
The only alternative would be that feng's ability remembers the HP the target was at right before it died, but that'd make it quite a bit worse.
