First of all, many people seem to confuse resistance and hit/miss. They are two separete things. When you cast a spell, the game first checks if the spell hits, misses or crits. What matters there is the level difference between caster and target. Stats and abilities that say increases chances to hit by something, or hit rating as it is called now, apply to this check. -resistance does nothing there. Neither does resistance on the target. Also crit is checked at the same moment. Meaning if you have 15% crit chance, and 95% hit chance you get on 100 casts on average 15 crits, 80 normal hits and 5 misses. A crit can not miss, but it can be resisted explained next.
If the spell hits, then the game checks for resistance. If that is 0, then there obiously is no check. If an item has -resistance on it, then it is reduced from the targets resistance before making the check. It can never be negative, so you can't get extra damage with reducing resist below zero. +hit% DOES NOT help here anymore. After the game calcuates the resistance level of the target it checks if the spell is a resist, 25%, 50%, 75 or 100% hit. The average damage resisted is target resistance / caster level * 15% up to a maximum of 75%, at 300 resistance for level 60.
Only exception are the so called binary spells that have an additional proc, like Frostbolt. It is either fully resisted or not resisted at all. The average damage reduction on both kind of spells are the same. Even though a frostbolt against a person with 60 frost resist has 15% chance of beeing fully resisted, +hit does not reduce that chance! -resist does. Many mages don't know that, and think that +hit% is more useful for a frostmage than firemage. That is completly untrue! Both -resist and +hit are equally useful for both kind of mages.
But to the original question: There seems to be some kind of holy resistance on some mobs. I have been doing a few ubrs runs with my holy priest using mainly smite and I sometimes see something like "Your smite hits X for 705 (235 resisted)
It's very rare, but it happens. The level difference would mean it gets totally resisted, so it's not about that. And if it was about some shield, it would say absorbed.
I don't think -resist is useful for a holy priest. It could be useful in PVP to reduce resistance of fear but it's marginal, not worth trading other stats for. For shadow priests it's a very nice stat as shadow resistance is pretty common and the increase -20resist gives in damage is about 5%, it totally owns +crit% especially for shadowpriests that cant crit with most of theirs spells, mind flay and dots.
+Crit for a holy priest is much less useful than +hit. A crit is only +50% damage so +1% hit will give 2 times bigger damage increase as it makes a miss become a hit per 100 casts while +crit only makes one hit become a crit. Surge of light is ofc nice if it procs and +crit increases chance of that.
There is just two things that make surge of light less useful. First of all it's bugged. If you chain cast smites it doesn't have time to proc before next cast start and your smite is not instant nor free and surge of light is still consumed. You can ofc cancel spellcast when you see it proc and recast but then you lost casting time. Even if a smite with surge of light is instant, you still lose 1sec global cooldown, half the cast time of a smite and even more if you canceled a spell allready beeing cast. When you consider all this and the fact that it can't crit, the increase in damage surge of light gives to continuous damage is very small indeed. It's a nice finisher in PVP though. If you happen to get a crit on a low hp player.
+hit increases in effectiveness depending on how much spellpower you have. With really good gear and talents you can smite for 1000 noncrit. That means +1% hit gives you 10damage increase, equal to +14dmg&heal. +hit does not increase amount of crits, that is important to remember. Crits never miss. With low gear you smite only for like 500, meaning +1%hit gives only bonus equal to +7dmg&heal. Effect of +crit is only half of that. Even with high spellpower crit is not very usefull for smiting priest. Take it if you can't get anything else in that spot, but don sacrafice +dmg&heal much for it. It also works the other way, the more crit you have the more effective spellpower is. If you have holy specialization and force of will and decent int you will be looking at 15% crit rate without any crit gear. So it makes your spellpower gear 7,5% more effective. Which you need to consider too when you compare +crit to +dmg.
You shouldn't take +hit% unlesss you have good spellpower allready, take more spellpower instead. Ofc best are items that have both. Personally I use Bracers of Arcane Accuracy and Cloak of Consumption for +2% while getting nice spellpower and stats too. I could use angelista's grasp for an extra +2% to hit, but belt of untapped power gives +29 spellpower, so it's better, especially against level 60 targets as +hit is capped to +3% against targets of equal level, giving 99% chance to hit, AG would only increase hit with +1% against those foir me. Raid bosses count as level 63, the base chance is 83%, so the cap is at +16%, but you wont be smiting raid bosses anyway. No sane guild would take a holy smiter to a raid to smite a boss. Holy priest mana efficiency sucks big time.
+hit becomes more useful in PVP as you want it to boost all other spells too, not just damage spells. A +3hit is very good to have in pvp.
by Arien < Final Equilibrium > - Aggramar
http://forums.wow-europe.com/thread.html?topicId=107621833&sid=1
