SD = Spell Damage, as indicated by "increases spell damage by up to <xx>" in item descriptors.
As detailed on the wikidot, most DK abilities scale with AP rather than spell damage, so itemisation wont be too much trouble for most DKs. Only Unholy relies on Spell Damage to a greater degree, but there's even a talent for that.
Spelldamage is obtained from the Unholy Tree via Impurity, a large talent investment but 20% AP>SD isnt bad and we don't have any idea on the final coefficients yet.
To be honest, as this is an alpha the talents should be taken as more of a statement of intent than a final tree. Blizzard clearly intend Unholy to be the SD-dependent tree, but intend to provide some kind of AP conversion talent to soften the blow. I expect Impurity to either provide an additional benefit or be reduced to three ranks like Mental Quickness for Shamans.
I concur that deep Frost is looking like the hardcore PvP tree... an AoE sap is just astonishing, particularly when combined with Death Grip to drag any errant healers into the area of effect before casting. That ability alooe has the potential to shut down half an Arena team, allowing focus fire on the remaining players and possibly winning a match. Compared to that, Unholy Blight just seems...lacklusre.
Incoming: a nerf to the incapacitate function of Hungering Cold, or a buff to Unholy Blight. As it stands, Unholy is a far poorer PvP tree than Frost.
Blood continues to stand as a solid melee DPS tree; it reminds me of the Shaman Enhance tree; lots of solid DPS talents, but precious little in the way of CC/anti-CC.
EDIT: With the recent changes to the Frost tree in particular, I submit
this as a revised deep-frost PvP tree. There are unspent points as wildcards, you can put them in Death Runes or Chillblaines etc depending on your playstyle.
Looking at the talents, the DK is heavily combo-based as the deescription states; get the enemies into a big furball, wait til you score a crit (for the guaranteed Howling Blast crit), Hungering Cold for a mass Freeze and then spank them with Howling Blast... six times base damage to everyone you can fit in the cone.
Edited, Jun 5th 2008 10:30am by Sinstralis