How do I win this fight, or at least improve my chance of victory from non-zero?
Pray he doesn't see you!
I played Priest at a high level, both PVE and PVP, but mostly PVE.
When I played PVP with my friends pre-made group, I had the hardest time against Shamans period.
Purge and shocks to stop your casting was hell.
When you cast your expensive buffs and/or shields, renew they purge it, which isnt good for your mana pool, not to mention purge was mana efficient, so basically a real counter.
In PVP, 1v1 situations was when I was Shadow because when I was Disc/Holy, I was assigned to a group and had help...
I'm sorry I could not be more help to you but many people here probably had more experience as Disc PVP than I did.
The one thing i do know is wand their damn totems, especially grounding.
Not sure if this is a neutral fight like a duel or in battlegrounds or out in the world?
Line of sight would be key while maintaining your dot.
Also not sure if your an offensive Disc or a support Disc priest just trying to learn to deal with shamans?
How do I win this fight, or at least improve my chance of victory from non-zero?
Be rich, engineering + major rejuvs, swappable spl dmg weapon (w/wizard oil) for offensive spells + drain mana +get Edward + Clutch of Foresight, cast r1 renew and other easy to get buffs to bait out Purge.
As an ele shaman, I have never lost a straight-up fight against a holy or disc priest. Shadow can win if they get a nice blackout proc.
What I'd recommend is something I don't really see people do. Kill the tremor totem and use fear. Cast Mana Burn to bait out earth shock and get some heals off. Then equip rocket boots or skull of impending doom and run away.
If you're lucky with mana burn you might get them oom before you die. In that case it should be a pretty fair fight.
- Memorize their cooldowns. Cast when these cooldowns are in effect.
Earth Shock = 6 second cooldown, 5 if talented.
Grounding totem = 15 second cooldown, 13 if talented.
- All shocks share the same cooldown. If you start running away and he uses Frost Shock to slow you, cast something immediately.
- Shocks have 20 yard range, stay at max range if he lets you.
- If he doesn't let you stay away, Wand or Melee his totems, prioritize Grounding Totem, Tremor Totem, Searing Totem.
- As jodiug suggested, get used to swapping spell schools. If he gets an interrupt off, it locks down just one of your schools. So if you were casting heals or Smite, you can still use Mind Blast or Mana Burn and vice versa.
- An ele will be casting his lightnings with 1.5s or 2s cast times. Kill his tremor during this time and fear him. He either gets feared or has to stop casting to recast the totem.
- While running around killing totems or LoSing his lightning, you can bait out purges with r1 renews.
- If he keeps purging your stuff, keep baiting him. You will win in a longevity fight.
- Have a Greater Nature Protection Potion handy :) Much better than what a Major Healing pot can do.
Engineering helps a lot. Stuns from nades/bombs, root from Net-o-matic, Discombobulator Ray to slow him so you can run at range/run away, and Flash Bomb if he uses Ghost Wolf to close distance.