Next week I'll hit 25.000 conquest points and the first thing I will do is exchanging all the haste gear I have with crit gear. I'll drop the 8085 haste cap and stack crit and int. Up until now I wasted some sockets by geming haste instead of intellect to get the haste cap. Now I'll gem only intellect to reach 17904 => mind Spike crits for over 75k in arenas on 65% resi players. To get as many mind spike crits as possible, I'll reforge into crit, crit only.
"From Darkness, Comes Light" makes 75k crits possible because of the 150% increased damage (which scales with intellect very well).
As opposed to "Solace and Insanity", you can do insane damage while moving with 2 instant mind spikes and 1 instant mind blast.
Since 5.3 hit, there are tons of physical-damage combs (namely hunter, feral, warrior, ret, rogue, monk, dk, enhancer). They will nearly always train you as a shadow priest. And when they do, it takes forever to build up 3 orbs and then when you start your insanity-mind flay you will get kicked or stunned (at least in 2000+ arenas). This is where your crit gear and "From Darkness, Comes Light" comes in handy. You just keep dotting everything on the field, while running away from the meeles chasing you. As a result you will get TONS of procs, especially in 3s. If VT is up on 3 targets, you can be sure to get 2-3 instant mind spike procs every 5 seconds critting for 75k each (if you are lucky). This causes extrem pressure, even though you are always on the run.
DP + 2x MS (instant) + 1x MB (instant) with VT+SW:P on the target, damages the opponent for around 250.000 damage in 3-4 seconds. Sounds op? It is.
I hope this helps some of you to get up some pressure in arenas, even if you get trained all the time.
edit: why I gave up the 8085 haste? I prefer 17904 int, 21% crit and 75k crits over the one additional tick.