--=-- SPELL PENETRATION & HIT DILEMMA --=--
I've seen a lot of questions about the usefulness of Spell Penetration stat on my realm and the overall of Internet. Some players say that Spell Penetration didn't work... Well, let see this basic concepts introduced by Blizzard (for patch3.3.5):
The effective resistance rating of the target was calculated as follows:
effective resistance rating(ERR) = Rb + max((Lt - Lc) * 5, 0) - min(P, Rb)
Rb - target base resistance (as advertised on the character sheet)
Lt - target level
Lc - caster level
P - caster spell penetration
Look at min() and max() functions! min(a, b) - returns the minimal value among a and b values!!! For lvl80 PVP Lt=Lc!!!! Then:
1.With Rb>P: ERR = Rb - P (with Gift of the Wild(75 resistances to all) you have the formula ERR = 75 - P);
2.With Rb<=P ERR = Rb - Rb = 0 ->> no character resistances.
Keep in mind, ERR is a relative parameter. ERR can be Arcane, Frost, Fire, Nature and Shadow (It's not universal!!!). (Paladins holy damage can't be resisted).
HOW IT REDUCES THE DAMAGE????
Damage reduction percentage (DRP) = 100% * effective resistance rating (ERR) / ( K + effective resistance rating (ERR) )
K = 400 for most lvl80 mobs and pl characters (seems). Then, if you have not any Spell Penetration:
1. Gift of the Wild (75 to all) reduces your damage to DRP = 100%*75/(400 + 75) = 7500%/475 = 15.8% !!!
2. Totems, Auras (130 to specific resist type) DRP =100%*130/(400 + 130) = 13000%/530 = 24.5% !!!
RESISTANCES TRICKS
Well, we can stack Spell Penetration in next order: 75, 85, 100, 130, 135 from enchants and gems. (75 SPe with 3xStormy Majestic Zircon or 85 with 2xStormy Majestic Zircon and Cloak Enchant: +35 Spell Penetration ). UrbanJuggernaut posted, that 130 is the cap. But how useful it can be for ele shamans?. Shaman's offensive spell are NATURE (Lightning Bolt, Chain Light, Lightning Shield, Earth Shock, Thunderstorm), FIRE(Lava Burst, Flame Shock, Magma Totem, Searing Totem, Fire Elemental) and only ONE FROST(Frost Shock) kind.
Main question: Who have a good protection against NATURE and FIRE???
1. NATURE: Hunters with Aspect of the Wild (130) and, of course, other shaman's :) Nature Resistance Totem(130).
2. FIRE: Paladins Fire Resistance Aura(130) and other shaman's Totem of Fire Resistance(130). --> IDK exactly about Mages and Locks fire resistances.
3. FROST: Paladins Frost Resistance Aura(130), DK Frost Aura(100??) and shaman's Totem of Frost Resistance(130).
Conclusion: With 85 Spell Penetration only Hunters, Paladins and other Shamans can reduce about DRP = 100%*(130 - 85)/(400 + (130 - 85)) = 100%*45/(400 + 45) = 4500%/445 = 10% elemental ehamans offensive spells(non-Binary) in duels, for exaple!!! Although resilience is generally considered to be a more useful stat when choosing between the two. So, resistances will stack only a few players probably. In most battlegrounds and arenas nature resistance is rarely applied, as I have seen... With 85 SPe we can cover the most useful and common druids resistance buff Gift of the Wild (+75 to ALL resistances!).
Recomendations: In most Worldwide, Duels, Battlegrounds and half of Arena matches 85 SPe is enought for elemental shamans. 130 SPe can stack hi-end geared (Wrathful set) ele shamans to gain 90-95% hit for shock spells and Binary Spells (if no else to stack is needed). Who needs 130-135 SPe? Well, I think only Locks and Shadow Priests(especially). In most arenas, party or raids there is always a Shadow Resistance(130) auras on everybody. Their offensive spells are Shadow based for Locks and ALL for Disco Priests.
SHAMAN'S BINARY SPELLS
They are: Purge (the best spell in WoW :D which removes 2 buffs), Wind Shear(interrupt spells, but not all; makes mobs less likely to attack you), Hex(CC into a frog for 10 sec), Roots(passive: from talent tree after ET; CC all!!! hostiles in 10yrd range for 5 sec), Slow(passive: after Earthbind Totem is dropped; reduces the speed for all hostiles in 10 yrd range for 50%).
Semi-binary spells: all shock spells( after damage they doing next effects --> 50% slows a single target - Frost Shock, 10% haste reduced - Earth Shock, DoT - Flame Shock(rogues cant hide with this debuff, opponents tremble awaiting Lava Burst :D).
Binary spells are spells which can only have full effect (hit) or no effect (resist); partial resists are not possible. Normally, damage spells are only binary if they have an additional non-damage effect. Some examples are Death Coil and Mind Flay. Frostbolt is no longer a Binary Spell.
For binary spells, both spell penetration and spell hit rating can be used to overcome resistances.
From official resource.
DoTs used to be binary spells, but this was changed.
Spell resistance was the second of two rolls to determine whether or not a spell was resisted. (Spell hit was the first roll.) The spell resistance roll would calculate in one of two different ways: one way for Binary Spells, another way for non-Binary spells.
Resistance reduced the chance for the binary spell to land by a certain percentage. Spell hit would not reduce this chance (hmmm). It was assumed that this percentage was exactly the damage reduction percentage given above
For Binary Spells is useful next formula:
Average Resistance (AvR) = (Target's Resistance / (Caster's Level * 5)) * 0.75;
- in this formula is not any Hit rating and SPe. Officially posted, that Hit not improves Binary Spell, but I have no evidience about how Spell Penetration improves Binary Spells...
Why is it called "average resistance"? For spells that have a non-damage effectÔÇösuch as slow, root, stun, purgeÔÇöyou'll either take the hit or avoid the hit altogether; these are examples of binary spells. The average resistance is the chance you'll totally avoid the hit. Adding the word "average" is a little redundant in this case.
However, when spells do only damage, it's not just a full hit or full miss situation. Pure damage spells can be resisted for 0%, 10%, 20%, 30%, etc. (in 10% increments up to 100%) of their regular damage. Your average resistance can still be anywhere betweeen 0% and 75%.
OVERALL CONCLUSION
For ele shamans below 6kGSPVP next stats are priority: Hit (5%) > Spell Penetration (85) > Haste > Spell Power > Crit > Stamina > Intellect.
Above 6kGSPVP: Hit(5%) > Spell Penetration(130 - 135) > Spell Power > Haste > Crit > Intellect > Stamina.
Spell Penetration is absolutely useless for PVE.
Elemental Shaman's PVE DPS, with less than 390 Hit (15%), suffers catastrophically.
P.S. Thanks for reading!