What are some things you should know as a Shadow Priest in WOTLK (PVP)

As the title suggests, post things that every shadow priest should know for PvP that might not seem obvious (be hit capped, duh). Tips can vary from "to easily beat a feral as shadow, dispel the druid clean so that you can dispel instant casts and barskin instantly" to a macro that makes your life easier fighting certain classes such as

"/castsequence reset=target/combat/8 Abolish Disease, Cure Disease, Cure Disease, Cure Disease, Cure Disease, Cure Disease"

which casts abolish disease on you and then switches to cure disease so that you can spam it.

Appreciate it.

My take on spriest pvp - just general tips that I'd give since I see people not doing this and generally having worse results in pvp:

1. Learn to move away / LOS enemy, while casting/dispelling. Learn which class you can "dps race" and which will kill you if you're both freecasting.
In general, dps classes vs which I move constantly (after putting dots ofc) unless enemy is in fear/cc or I see I'm winning anyway:
-Pala
-Warlock
-DK
-Mage
-Rogue
-Hunter (both towards hunter and out of LOS)
Classes vs. which moving is situational:
-Warrior
-Priest
-Boomkin druid
Classes which I can dps race or moving is usually pointless:
-Feral druid
-Shaman

2. Learn vs. which classes you should be aggressive with cooldowns, ie silence/stun/disarm/dispersion. This usually then is combined with point 1 above.
Some of the example where I open with a cd:
-Hunter (stun, sometimes dispersion if its PVE hunter in bg)
-DK (silence)
-Spriest (silence)
Examples where I usually wait:
-Mage
-Any healer spec

3. Have 2 different keybinds, one for offensive dispel on target/focus and one for defensive dispel, on yourself or arena mates. Learn which movement slowing effect can be dispelled and for which you need to fade.


Other than this its the obvious "know what other classes can do" tip.
Like, for example, I have a goal and a plan for a duel vs. a ret pala, assuming standard play 1v1:
Goal = get to the 2nd fear. Pre-shield/renew/prayer of mending if given time. Fear + VT + move away putting other dots. Wings mean stun + dispels, keep moving. If I get to my goal (2nd fear, 23 sec) with my dispersion unused - the fight is an easy win for me. If I had to disperse but got to 2nd fear its mostly still a win.
Like even classes that I usually lose to (like UHDK) - my goal is to mess up their standard pattern somehow, since I know I die to correct play from the DK. This usually means some combinations of points 1 and 2 above.