Hey, i dont know if this has been posted or not, but here it goes.
On alot of the WoTLK servers out right now, DKs are pretty bugged. The thing is, you can stack spell damage on a death knight, by using spell damage gear, and then putting the enchant "Razorice" on your weapon. The razorice will proc and will do alot of damage due to all the spell damage. On my server, VCN, you can also spam Icy Touch because i think the rune cooldown is bugged and it doesnt go on cooldown. Icy Touch crits for like 2.3k alot of the time.