You don't need to Festering at all. Howling Blast your Frost Runes away, Necrotic Strike your Unholy/Death Runes away and dump Runic Power into Frost Strikes. If the target is sub 35% and you think you'll kill him use an Obliterate if you have the runes. If there are no heals you can just put 1-2 Necrotic Strikes on the target to absorb that classes self-healing and Obliterate them down.
http://www.wowhead.com/talent#j0hZGc...0ubG:Mma0qVMm0 - is how I spec you can sub Obliterate glyph out for Frost Fever if you don't plan on using Oblit often.
Make a macro to Lichborne heal yourself.
/cast Lichborne
/cast [target=SELF] Death Coil - Works for me. Obviously put your name where SELF is.
Reforge so you have as close to 5% hit as possible, wowreforge or other reforge tools can be used or you can just wing it like I do. After that reforge everything to Mastery so your Howling Blast and Frost Strikes hit harder. As Human, I use the 2 resil trinkets, one with Strength proc and the other with Strength on use. I think these are the best since DK's are kind of squishy and it isn't really worth it to use a PvE trinket. Macro the on-use Strength with Pillar of Frost for maximum burst potential.
/use Cataclysmic Gladiator's Badge of Victory - Replace Cataclysmic with Ruthless if you have to.
/cast Pillar of Frost
As far as gemming goes, if you only intend on doing battlegrounds I'd go with all +40 Strength in every slot. You could swap Resplendent's into Yellow if you feel you're lacking Resilience. You will also need 195 Spell Penetration so either put 2 epic Stormy Deepholm Iolite in your blue slots + Spell Pen Cloak enchant. If you don't have enough gold just put 3 Stormy Ocean Sapphire's in the 3 blue slots with the cloak enchant. This insures you will never see "Resist" unless someone has more than 195 Magic Resist which shoulden't ever happen. Buy the hit neck, mastery cloak, haste bracers, mastery belt, and haste boots over the other options. If you intend on doing arena, I highly suggest investing in some more resil. Either 40 STR in red, 40 resil in yellow or all out
20 str/20 resil in red, 40 resil in yellow, 2 63 spell pen in blues, and 40 resils in any other open spaces (belt buckle, 3rd blue slot, Blacksmith slots if you have those).
Overall Frost is a very fun spec but Unholy is better for arena if you plan on going down that path. That's not to say Frost is bad, Unholy just suits more comps because of various tools. You won't see as big numbers as Frost though, which is part of the fun. Obviously if you're rich enough invest in epic gems over the 40 str 40 resil ect that I suggested if you have it. Good luck and enjoy.
Other notes on things you can do:
-When you pop your Pillar of Frost macro, immediately use Blood Tap to get that Rune that was used for PoF back.
-Use Raise Dead and quickly use Death Pact if you're desperate for a heal.
-Hungering Cold in the middle of big groups to land a huge CC.
-Try to save Empower Rune Weapon when it will give you all 6 Runes back.
-You can spam Chains of Ice on melee to kite them when you're low because of the root.
-If there is a healer present, always use Necrotic over Obliterate. Especially if it's a big team fight, the big snare on the ground will be useful to someone.
-Death Grip interrupts a cast so if you're in a bind with Strangulate and Mind Freeze down or you're simply out of range of someone casting you can use that to stop them.
-When facing a somewhat skilled healer who is juking (canceling his cast bar in hopes you will use Mind Freeze) just save your Mind Freeze for when he's very low with a big Necrotic stack on him. If he jukes you, Strangulate his next cast. If he trinkets or doesn't die, Death Grip the next cast. Mind Freeze should be up again if he is still not dead.
-When heading into a battle your skill usage should usually be like this:
Howling Blast to slow/apply Frost Fever, Pillar of Frost macro then Blood Tap, Necrotic Strike 4x in a row - if you get a Killing Machine proc use a Frost Strike in between Necrotics, Frost Strike the rest if your Runic Power away. Runic Empowerment talent has a 45% chance to refresh a rune when you use Frost Strike, pay attention to which one it does. From here on out, follow this priority. No Frost Fever? Howling Blast. Killing Machine? Frost Strike. Frost Fever is up but no Killing Machine - spam Necrotic until you're out of Unholy/Death runes. No Runes left, spam Frost Strike.
-Blood Boil and Death and Decay can be used to take Rogues out of stealth.
-Land Strangulates mid cast for a 7 second silence via Glyph of Strangulate.