Atm it feels random. The info says it enrages when I summon him and also when I stun, as in 2 different cases. So I'm not asking about the summoning that stuns, but the case where Tibbers is already summoned and I get my stun up again and use it. He enraged on a totally different person that I did not stun.
And I also want to know what happens when I die, does he enrage and attack the killer or some other player that's closer?
Enraging doesn't mean that he targets a specific player, it just means that he gains bonus attack speed and bonus movespeed. So if you stun a champion with your passive when Tibbers is already summoned, he enrages getting that bonus as and ms, but he will continue to attack his current target. If you want him to attack someone else, you need to control him to do so, either with alt+right click or using R again.
When you die, Tibbers will enrage and attack whoever killed you, but if that player is to far away or dead, then he will attack the nearest low health champion instead.
