Good, things are getting spicy.
It makes sense for all dragons to gather in the Dragon Isles. No more Deathwing, no more Old Gods, their land is available, a common enemy returned, etc. I like this.
On the other hand, it is about time someone stops Wrathion. I think the character is excellent, but Wrathion does whatever without assuming any consequences. I just hope that this tension among black dragons continues, and Sabellian isn't killed just to favor Wrathion.
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Edit: or maybe Blizzard is setting the stage for "evil" dragonflights counterparts? 5 versus 5?