One of the key components of taking on a warrior as a priest relies on proper use of Psychic Scream, and this is regardless of spec.
Pop your first fear ASAP, and then use it again one it's off CD. Your friends should be peeling off you, and forcing him to use his trinket early so you can full duration fear on the second Psychic Scream cast.
Surviving that first 30 seconds isn't difficult. Bubble, keep renew on you, PoM and use IF to heal yourself. A good warrior will know to stun you when you use IF though.
Save Pain Suppression for that stun, remember you can cast it on yourself while stunned.
Here are some key things you need to do or work on:
- Fake casting, make sure inbetween fake casts you cast a PoM, PW:S or Renew so you aren't wasting the GCD.
- Use of mind control to bait the pummel, 9/10 times they'll either pummel it or sit in a full MC while you can recover all small cds.
- Trading CDs.
i.e PI when pummel is down to catch up, or when he uses bladestorm/deadly calm. Pain sup if you can't trinket a throwdown/his big cd's (recklessness, death wish, ect) Barrier is hard, but some times a warrior can be predictable and you can pre-cast a barrier into a throwdown.
- Positioning, when ever you shield yourself you need to be trying to get away from him. Around corners ect. Get slows/Stuns/Nova/Snare from your partner and you have a bit of breathing room to top yourself up.
If you aren't grab an addon (as previously mentioned) called "Juked" it'll show you when interrupts are down/up, you can add spells ect. It's a must. (Or a similar addon)
A lot of beginners and well, everyone tends to use another addon called "GladiatorLosSA" which you can configure to your liking but it will vocally announce any cd's you have it set to, i.e "Recklessness" will be called out for you. Saves watching for spell animations.
Fake casting and timing your PS for the trowdown/reck, its that simple.
One more thing I noticed wich is kinda funny is if you never use your inner will some warriors wont use throwdown, cause they are allways saving it for your inner will.
Been having some long games against arms warriors without them using throwdown, dont think they think about it before they see the inner will.