Ascendant council. After dropping all 4 elemental to 25% (well, 2 of them), they merge and form a big bad elemental boss.
And while we are at it, is there any reason to bother with the debuff mechanics in the first phase of Ascendant Council encounter? My guild just dispel them right away and zerg the boss down.
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About that fight being easier on 10m, I can imagine certains mechanics being harder (chain lightning), but losing a single dps to random ice lances (or anything) meant a wipe at ~3-5%. I'm not sure how many death you can afford on 25, but the fight still gave us lot of trouble.
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