He's interesting. Not sure how useful he'll be in arena though, as most of his kit wants him to be damaged to be effective, and in arena, chances are if he's damaged, he's dead (and so is the rest of your team).

Unfortunately for him, he's ATK-based, which means you can't even resort to tricks like gearing him heavily defensive-based and hoping to outlast the other guy.

Ultimately, I'd say Dark Elhain is better, for two main reasons. Firstly, Dark Elhain puts a 50% ATK buff on herself before attacking, which means you don't need a dedicated ATK buffer on your team (although if you have Arbiter, this isn't really an issue). Secondly, she absolutely crushes Tormin teams, which are one of the main non-speed nuke teams. Also, less important, but the multiplier on Dark Elhain's A2 is *slightly* better, at 3.8 instead of 3.75, and Dark Elhain is quite good for Ice Golem as well.

First epic i pulled! and used a lot, his single target  hits really hard, and his turn meter control is nice, but he was better in dungeons than arena for me

I do not get anything good.