Raze is a member of Black Ring and in charge of one of the Flying Fortresses you can enter from Orobas Fjords. The entrance is on an outcropping on a cliff facing Champion Harbour. His fortress is surrounded by lava, but when you meet him, he complains that it's much too cold for him. None of the responses have any impact on the coming fight, so choose one that feels right to you. This Battle should be fairly easy, only it can become very frustrating very quickly. When you get Raze down to 50% health he will quickly try to run to one of two healing booths. There then follows a small cutscene that prevents you from taking any action at all. Raze will respawn inbetween these booths with 100% health. two other booths also constantly spawn walking armours, but these are more of a nuisance but with targetting being as shonky as it is, they can interfere with your battle with Raze.
The solution appears to be switching these healing booths off. However this off switch is (I have no idea why) set to 15secs So...basically you have to be able to take down a 30lvl boss with adds in 15 seconds from deactivating the booths. There is no point camping these booths as you can't be two places at once. Camp one of them and he simply heads to the other. You can hope to draw Raze to a booth you deactivated in the hope that he will have longer to run to the one that is active. But this will be a long fight as his healing booths are limitless in capacity.
The fight is quite simple all you have to do is deactivate one when he is at about half health then when he runs to the active booth deactivate that one and go camp the other.
What little is written in various forums and FAQs seem to suggest this fight will come down luck mostly. Your level will be a factor as will be your character build. My own thoughts are that a combination of all the above, while letting his little friends gather round you; along with any summoned pets of your own, may create enough of a log jam that Raze can't escape quickly enough to heal himself.
Mindread Raze to learn about his Ulthring Boots he's wearing so he drops them when he finally keels over.