Picking between these two gems has been driving me crazy, allow me to outline why.

Point for Point, i'm fully aware that +hit is the better stat that I can get all the way up to the +hit cap for boss damage. However, it seems that more encounters are being designed with level 61-62 adds as the focus or challenge of the fight. ~40% of my damage during karathress was done to adds, an even higher % for tidewalker. These are just examples. In these cases, the effectiveness of my +hit was effectively reduced by ~40%.

According to Dr Damage, 12.62 hit rating is worth another 15.9 damage for my character. This is with the two-roll casting system enabled for Dr. Damage. This means that 1 hit rating is worth 1.26 damage, i'm just going to simplify things and say that at 1:1, hit rating is better than spell damage by 25% vs bosses. That seems like an accurate statement.

So assume that during a fight where 30% or more DPS was done to non boss level mobs, would I be correct in assuming that living rubies would result in more damage than veiled topazes? I ask because my guild has put in a day on vashj, and it drives me nuts when i'm not sure if i'm outputing my real maximum. For those who have done the fight from start to finish, would you say that 1/3rd of your damage is done to adds? Right now, i'm pretty sure i'm going to replace my many topazed sockets with rubies before our next day of attempts strictly because dps during phase 2 seems much more important than phase 1 and I assume phase 3.

Anyone else run into this selection problem? Why do YOU use one over the other?

The easiest solution for this problem is to get the Eye of Magtheridon. With that trinket 1 dmg ~= 1 hit rating, so you loose nothing by going for the Runed Living Rubies.

Also, as far as I know nukes use a one-roll system, not a two-roll one. Which also diminishes the value of +hit a little.

I've seen for myself that it's a two roll system, one roll to hit, then a second to determine if it crits. I have gotten combustion up to 70%, which combined with my crit rate is over 100% crit chance; and then I got a resisted spell.

I'm not saying to abandon +hit altogether, just to opt for +dmg gems; gear can be swapped out for the appropriate fights. I'm just unlucky in that some rather critical +hit pieces haven't dropped for me, so i'm stuck at what feels to me an uncomfortably low +hit chance. I'd still want to have a +hit heavy gear set for those fights where you do spend most of your time on a +3 mob, no doubt. For the same reason of optimization, i'd want a +dmg heavy set for those fights where I have to focus on adds.

I seem to remember, a year and change ago, a post from Tseric on the mage forums (around the time ZG was released and questions were raised about the +spell hit items that were being introduced) where in quite a bit of detail he explained that spells were, in fact, using a 2-roll system. The first determining whether or not the spell would hit or miss, the second determining resists (none/partial/full).

deleted: double post

This was white resis due to spell hit and yellow resis due to yellow resis message - this was also changed and the actual mechanics of the new yellow only resis was never actually pubished. Most agree that it is a 2 roll system though - first of all one to see if it hits and another to see if its crits/partial resis's.

You mean first roll only checks (HIT or RESIST) and second roll checks (CRIT or HIT or PARTIAL RESIST)?
I have at the moment no evidence but I am fairly sure I often had a partially resisted crit. This wouldn't be possible with the described system.

I always had the impression that the second roll only checked against resistances and lead to partial resists distributed in a way that the average resist is proportional to the mob resistance (or binary resists that averaged out for the same value.
The first roll in the other hand works the same as for physical damage, meaning it decides if the spell hits, crits or misses (= full resist).
In this system the first roll is affected by +SpellHit (resists become hits) and +SpellCrit (hits become crits) and the second roll is affected by SpellPenetration/Curses (partial/binary resists average out at a higher value).

Has anyone tested the actual game mechanic to correspond with one or the other? I am not sure but think the second fits my own experiences more closely.

All that shows is that if it's one-roll, resist is higher priority than crit, which Loatheb and warrior tanking mechanics have shown to be true. With a 1-roll system, +crit only converts hits into crits, and nothing else.

Good point. While I haven't tested it personaly so I don't like to cite it:


Spell Hit, Spell Crit and mages
Post #40, don't know how to properly link to that

Quick test by Mylek that proves it's a 2 roll system. I'd like to repeat it myself using a character with a higher crit chance, but until someone tests and shows otherwise, spells use a 2 roll system.

I blame blizzard for putting up resist when we miss, it confuses people too much. (totally uneeded)

2 rolls (3 in total)

Roll 1) Hit or Miss (resist is checked here for binary spells)
Roll 2) Crit or no crit
Roll 3) If a direct damage spell check for partial resist. (0%/25%/50%/100%)

Hence you can see crits that are partially resisted. (100% (full) resist being one of the possible outcomes)

As implied in the original blue post, the partial resist for DD spells is checked on impact. So I'm not so sure it is a third roll for you so much as a roll on the targets part seeing if they will partially resist the DD spell based on resistance values for the school.

Several people (like the previous post) have tested this with low level characters and got the same results. It is not 100% for certain because those who don't agree just point out that boss mechanics are different and it is near impossible to get a significant sample size on bosses to prove it one way or the other. (and trying to hold other variables constant)