Immolate critting: It's that big

I don't actually mean big in terms of DPS. It's actually kind of medium at that, but I'll cover that momentarily.

It's big because it's a significant design decision by Blizzard. Immolate, as it stands on the PTR, does not require a talent, glyph, set bonus, or any outside utility. It is capable of dealing critical hits in its BASE FORM. If that doesn't excite you yet, read on for the implications for other specs as well.

It's only the second periodic damage spell in the game capable of doing this, and the first was Conflag, which is a talent itself anyway. This has wide implications for warlocks as a whole - from level 1 when you go to your trainer and spend those first precious 10 copper for Immolate, you have a DOT capable of critting.

Of course, your crit rate is dick like everyone's at level 1, you'll probably hit level 5 before you even see it crit, but the point is less the DPS gained by level 1 warlocks and more what this change means for other spells. It means the "glyph/talent/bonus or gtfo" rule of periodic damage crits isn't set in stone. There's hope yet for Cataclysm killing off talents like Pandemic. Hell, Shadow Form's tooltip might fit on screen in the future.

What it means RIGHT NOW
Short term... This doesn't mean as much. It will solidify immolate as the life tap alternative glyph for destro, glyph of imp's days are numbered at best. Immolate is slightly over 7% of destro's DPS. With BIS crit rates, it'll be gaining around 30-40% damage (remember the nuke portion can already crit, only the relatively weak periodic damage is actually going up).

Demo gets a nifty boost from this as well, with it's high crit rate getting packed onto extra ticks. However, immolate is less than 6% of demo's DPS - demo is a heavily nuke favored spec, arguably moreso than destruction (corruption is there more for procs that benefit nukes than for periodic damage). While this is certainly a nice boon for demonology, leave your glyph of immolate at home, you're not getting away from glyph of life tap, even at next to no spirit from gear. Base plus raid buffs is enough to keep it in the number 3 spot.