after entering Lagon’s room for the first time to start the fight i ran around to see if i missed anything and in doing so i ran outside his range before he close it in with his tentacles but that also meant i couldn’t get near him again. Luckily i’m an archer so it doesn’t matter for me but if i was close range only i couldn’t have killed it.
This is a known problem with Lagons arena and usually happens with a movement skill bypassing the barrier if actioned in just the right way… Variations on this issue happen often with minions/pets too…
Old Lagon is in need of some TLC and the devs know about all his little foibles…