Some players were finding themselves at the mercy of the random number generator on the Blood-Queen Lana'thel encounter when she used Pact of the Darkfallen. This ability links three raid members with glowing red spheres and until the three meet up at a point they will do AoE damage to all other players near them. This fix will spread the damage out over more 'pulses' which will reward players that react quickly, since they will be able to get away from their fellow raid members. This change probably wasn't necessary, but it won't hurt or significantly alter the encounter.
The DK glyph of IBF will let Death Knights that aren't tanks retain significant utility from IBF. The ability currently bases the amount absorbed on the defense rating of the user, which made it far less effective for DPS DKs. This will be a significant buff to Death Knight survivability, but I only really see it being worth a glyph slot in PvP situations.
The Priest 4 piece buff is a testament to the fact that there is in fact a critical mass to forum whining that will deliver a result! Priests had been complaining since before 3.3 that their 4 piece set bonus was worthless, and have got a significant buff to it. It's still not as powerful as some of the other set bonuses, but this is much better than nothing. Maybe Rogues will take a hint?
The remaining glyph changes make you wonder who exactly thought that these changes would convince players to use these glyphs. The Paladin one is alright for Arenas, because they don't have many options, but the Rogue glyphs... really? There are simply too many more interesting or more effective glyph options out there. Is a two second buff to the 10 second increase on expose armor really going to be the tipping point for anyone? Maybe! But I'll have to see it to believe it.
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