We did this for the first time last night and for anyone reading this article having conniptions: you absolutely do not need arcane resist for this encounter. It felt very easy, we killed it in 3 pulls and our two wipes weren't as a result of excess incoming arcane damage.
100% do not need arcane resist for this fight.
As others have said, you dont need Arcane resist at all.
didn't need resistance back then, don't need it here and now.
Didn't he have a non-unique model on first release for his dragon form?