Tier 6 4-Piece Bonus, Which Pieces Are Best?
While the 2-piece bonus for warlock Tier 6 gear (aka Malefic Raiment set) is relatively useless, the 4-piece bonus is extremely good. To find out how much, let's go back to our Leulier spreadsheet. If you have the T6 4-piece bonus, then cell B5 on the "Advanced infos" tab will say "TRUE". Write down your current DPS value, then change this cell to say "FALSE". Now write down your new DPS. The difference between these two numbers is the DPS increase because you have the 4-piece bonus. For me, this turns out to be 129.33 DPS. Be sure to not save you changes when doing this test, or you will lose the formula that is in cell B5.
So the question becomes which 4 pieces of T6 gear is the best combination. We need to compare each T6 piece to the highest DPS item for that slot. Therefore, we want to minimize the DPS loss by wearing 4 pieces of T6 instead of 4 higher DPS pieces; if we can't minimize the DPS loss to less than the 4-piece bonus, then we should not wear the 4-piece bonus.
So what are the 4 pieces that will minimize the DPS loss caused by not wearing better gear? To answer this, we will compare every T6 piece with the highest DPS piece for the slot. I will be using the following DPS values from my Leulier spreadsheet; I will also disregard any DPS from + spell hit because you can always get enough spell hit from other items and/or gems.
+1 stamina = +0 DPS
+1 intellect = +0.20 DPS
+1 spirit = +0.11 DPS
+1 spell damage = +1.10 DPS
+1 spell hit = +1.78 DPS
+1 spell crit = +0.84 DPS
+1 spell haste = +1.11 DPS
+1 MP5 = +0.30 DPS
Chest:
[Robe of the Malefic] - 116 DPS
[Fel Conquerer Raiments] - 193 DPS (+77 DPS)
[Sunfire Robe] - 218 DPS (+102 DPS)
Gloves:
[Gloves of the Malefic] - 88 DPS
[Sunfire Handwraps] - 126 DPS (+38 DPS)
[Gloves of Tyri's Power] - 128 DPS (+40 DPS)
Helm:
For the helm comparison, we will ignore the meta gem since they both have one.
[Hood of the Malefic] - 127 DPS
[Dark Conjuror's Collar] - 176 DPS (+49 DPS)
Legs:
[Leggings of the Malefic] - 130 DPS
[Leggings of Calamity] - 202 DPS (+72 DPS)
Shoulder:
[Mantle of the Malefic] - 92 DPS
[Amice of the Convoker] - 152 DPS (+60 DPS)
Boots, Belt, & Bracers:
Each of these T6 pieces drop from Sunwell Plateau. Even without the spell hit rating, each of these pieces are the best in slot pieces; there are no better pieces than these.
[Boots of the Malefic]
[Belt of the Malefic]
[Bracers of the Malefic]
Conclusion:
It is obvious that the T6 boots, belt, & bracers are certain choices to wear. So now we just have to determine the best choice for the fourth piece. Let's list the DPS loss for each of the T6 pieces we are considering for this spot:
T6 gloves: -40 DPS
T6 helm: -49 DPS
T6 shoulder: -60 DPS
T6 legs: -72 DPS
T6 chest: -77 DPS (or -102 DPS if you are a tailor)
A quick glance at the DPS losses above will show that only the gloves and helm are close to being the best choice. The chest, legs, and shoulder pieces can be replaced with better gear for a larger DPS increases than the gloves and helm can be. It should also be noted that both [Dark Conjuror's Collar] and [Gloves of Tyri's Power] are drops from Kil'jaeden, so it will likely be a very long time before those drops are even available to you. However, the 2nd best hand item, the [Sunfire Handwraps] are easily crafted at this level.
Theoretically, the best four pieces of T6 gear would be the T6 boots, belt, bracers, and the gloves. However, given that the best helm in the game is a drop off the last boss in the game, your best choice will likely be the T6 boots, belt, bracers, and helm with the [Sunfire Handwraps]. These 4 pieces have a loss of -49 DPS, but the 4-piece T6 bonus gives +129 DPS. The net bonus for me is +80 DPS. Assuming you are also a destruction warlock, your results are likely to be similar.