RG Live WotLK 3.3.5a

https://youtu.be/Of-Z2YGxUvY?t=58
1.0M HP -> kommt runter und springt wieder auf 1.1M

https://wowpedia.fandom.com/wiki/Scourgelord_Tyrannus?oldid=2363774

After some dialog, he will hop off of Rimefang, heal to full, and engage the party on the ground. Rimefang will continue to fly overhead during the battle but cannot be targeted. Note that Tyrannus heals to full as soon as he dismounts, so don't bother attacking him at range until he's on the ground.

Angreifbar sollte er zwar sein, sodass man schonmal Debuffs setzen kann, allerdings soll er sich dann auch nochmal vollheilen bevor es losgeht. Aggro wird nicht resetted.