Glyph of Demonic Armor
Reduces the mana cost of your Demon Armor by 50%.
I'm not a big fan of cost reductions to preparatory spells, specially not to a class that can cannibalize health for mana. With Demon Armor now undispellable, reducing its cost has no real impact. Probably the most uninspired of all the glyphs in this batch.
Glyph of Fel Armor
Increases the duration of your Fel Armor spell by 30 min.
It's basically the same as the Demon Armor glyph, but this is slightly better if only because you no longer have to cast as often. It's not like 30 minutes was difficult to micromanage, but what can you do?
Glyph of Kilrogg
Increases the movement speed of your Eye of Kilrogg by 50% and allows it to fly in areas where flying mounts are enabled.
This glyph falls squarely into the category of 'too cool'. The ultimate voyeur spell, the best part of this glyph is allowing the Eye of Kilrogg to fly. I know, it's not usable in instances, where the Eye is also utilized, but this is just an awesome spell for scoping out areas in Outland and specially Northrend. Without the ability to fly for the first 7 levels in Northrend, being able to scout areas or look for particular mobs with flight is an incredible advantage. It might be good for giggles in Patch 3.0, but it'll be invaluable while leveling in Wrath. It's even good for Warlocks still grinding to 70 in Outland. The faster speed is just a bonus.
Glyph of Souls
Your Ritual of Souls spell no longer requires a Soul Shard.
With this glyph, there's no more excuse not to drop a Soulwell in the Battlegrounds. Not that there ever was one, really, but this is another one for those lazy bums! Pretty useful for those times when you keep wiping on a boss, which usually finishes up shards without the opportunity to get more.
Glyph of Inferno
Increases the Fire damage of your Inferno spell by 50%.
A whopping 50% damage bonus! Awesome! Ok, no, not really. Not that we see Inferno used often, but when we do, it certainly isn't for the fire damage. An additional second to the stun would've been better. Alright, so maybe the glyphs this round aren't quite as impressive as the last one... but at least there are some very practical ones and a cool one. A flying Eye of Kilrogg! How can anyone not love that?