With regard to Miragul's Planar Shard, the only MOBS in the zone that have a more difficult mode are Haladan and Miragul himself. During the Haladan fight there is a point at which he asks you to make a decision, which allows you to complete the encounter in easy mode or continue on to fight enraged versions of Haladan and Tuskers (hard mode). Hard mode encounters have their own loot table, and do not share items with their easy mode counterparts. When you get to the final floor, near the spiral staircase, you have a conversation with Miragul himself during which you can either insult him and he will fight you himself (hard mode), or let him make his speech without insulting him to get easy mode (his menagerie).
In addition there are items available from some of the Everfrost group instances that can affect aspects of the first floor encounters, giving players an additional advantage on the first floor. These are not needed to complete the zone, and have no effect on the treasure dropped by encounters they affect.
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