Hellord explains it much better than I can - taken from the Fury War thread:
Originally Posted by hellord
Armor penetration works on the smallest between armor (After debuffs like ff, sunder and st) and (armor+c)/3 with c=15232.5 (relative to a lvl80 attacker). Whenever your target has more than 7616 armor you are not able to completely negate his armor DR.
Bosses have 10643 armor, 8089 after sunder and FF, so 100% arp will ignore the boss armor down to 315 (~2%DR). Shattering throw wll bring this value to 6471 so 100% arp will be able to go through the whole armor and you end up gaining that 2% additional damage.
For any target that has 7616 or less armor is not even needed a debuff on the target because 100% ArP will ignore the whole DR.
Generally I find you should gem for socket bonuses if they just have red and yellow sockets, whereas if they have a blue socket I generally agree with the above poster. If they had 2 blue sockets (don't know if this exists on the current gear) I would probably gem straight spell power (or spell power haste if reckless were better than runed, which happens sometimes). Of course rawr is always the thing to check with this kind of question though.
Last night I upgraded to my 4 peice T10 set (replaced my 245 chest/gloves for 251). Prior to this I was at 905 haste, 340 hit, and 33.39% crit, and after was at 824 haste, 274 hit, 37.10 crit. I piddled around with the heroic dummy for a bit, but my dps with the 2pct9 bonus peaked about 300 higher than my 4pct10, and I can't figure out if it's due to loss in haste (Which would possibly allow for more LO procs?) or hit rating (I'm a draenei.) Thanks for any help in advance.
I apologize in advance if this has been covered somewhere, I'm a long time reader and haven't came across specifics yet.
"A non-Reaping build/rotation is utilized in the ilvl 245/258 set weights, while a Reaping build/rotation are utilized in the others, to best reflect what's most optimal at those gear points."
"Once you attain 2P T10 and/or several pieces of ICC gear, Scourge Strike scales upward enough to make Reaping a dps gain once again, making this build the most optimal for single targets."
Are there any specifics on actual stat weights to justify the spec change? Do you have to obtain a certain ArP Rating to get more dps out of the T10 build?
I don't have exact numbers, but I can tell you that for me at least, 2pc t10 wasn't quite enough to make reaping a win. I had very low armor pen, due to being geared for 3.2 unholy. I did go ahead and swap to reaping when I got 2pc though, as the difference was only ~15 DPS between reaping and non reaping, and with my tree druids trained to revitalize me, the extra GCD's you gain from the reaping build always results in death coils =P
Your best bet is to simply sim it for yourself, and take into account that a reaping build has more free GCD's. More free GCD's means more potential death coils, so if you have some trained tree druids or are on a fight where you can use AMS to soak up RP, reaping will surpass non reaping as long as they are fairly close. More free GCD's can also help if you have bad latency, too.
Thanks all for the advice about using 2 tanks. Swapped back to that tonight, and it was so much easier in p3. We both used frost resist anyway, since Sindragosa hits like a girl so it made sense to reduce the big breaths, and after a few more goes to show some new people the fight, we were standing over her corpse. So for my raid's gear level at least, 2 tanks is definitely the way to go.
Read the OP on explanations on how the gemming AEP works for Blood; I promise you that Strength isn't capped, and at your gear level gemming for ArP is questionable.
On the gear issues, downloading RAWR is my first suggestion, as it looks like it could help you quite a bit. Consider that triggering a setbonus, indipendently on how good it is, will generally always tip the scale in favour of the setpiece when compared with loot of inferior or equal iLVL.
I totally agree, common sense seems to suggest that getting your Str well over 2000 and then gemming for Arp is the way to go, but having said that, adding lots of Arp at the expense of Str even at lowish gear lvl's seems to also work.
RAWR seems to think that adding the belt and then re-equiping Darkmoon Card Greatness is slightly better than the 2 T10 bonus probably because the T10 helm is almost identicle to my current helm (no stat upgrade).
So a little testing is in order, belt and card will give a big Str boost, so I shall see what differance it makes.
I dont think I am meeting my gear potential, but I have no idea what I should be doing differently. I was hoping someone could take a look at this latest combat log and give me some pointers, or just point out anything you notice.