Originally Posted by Aldriana

EP stands for Equivalence Points. It is a means for comparing stats - the notion is that if two items have comparable total EP values, they will do similar DPS and are thus roughly equivalent. By convention we assign 1 AP a value of 1 EP, but you could base the system off any stat - in point of fact, a lot of early rogue theorycraft was done using Agility Equivalence Points (AEP) - which is where the name comes from - with the convention that 1 agility has a value of 1 AEP. But there are problems with this approach, and more recently the convention has been to use EP based off 1 AP = 1 EP.

Regarding Tricks: so, from a purely theoretical perspective, it is a raid DPS gain to use TotT on *someone* every cooldown. If anyone is remotely close to being threat capped, you should use it on the tank to prevent threat capping; if everyone is safely behind the tank, you can Tricks whoever you want without aggro issues. In the OS+3 scenario: by the time you kill the drakes and stuff, the MT should have an insurmountable aggro lead by the time you get back to Sarth, so you should be able to Tricks DPS safely. In terms of an actual crossover point: it's sort of a judgement call. If there are DPS at 99%, you clear want to tricks the tank; if no one is above 50, you clearly want to tricks the DPS. But what about 95%? Probably still tank. 75%? Probably still DPS. But whether the exact line is at 80 or 85 or 90 or whatever sort of depends on the fight and your guild.