One of the dilemmas Frost DKs may have encountered in Firelands was whether or not to put talent points into Chilblains (slows targets affected by Frost Fever) and Endless Winter (makes Mind Freeze cost no runic power).

Personally, I completely got rid of Endless Winter, since Alysrazor was the only boss with anything to interrupt, and it was simple to just make sure you had enough RP for interrupts. I did keep Chilblains, however, because it's amazingly useful for dealing with Beth'tilac's spiderlings.

So how useful will these talents be in Dragon Soul? Here is a chart of which fights you might use either of these abilities.

Dragon Soul Boss	Chilblains	Endless Winter
Morchok Yorsahj the Unsleeping Warlord Zon’ozz Hagara the Stormbinder Ultraxion Warmaster Blackhorn Spine of Deathwing Madness of Deathwing	No No No No No Yes No No	No No No No No No No No

...yeah. Pretty straightforward, haha. Get rid of Endless Winter for sure, and as for Chilblains? It depends on your raid comp. Definitely keep it if your raid lacks slow for dealing with the Twilight Sapper adds, since you'll be Howling Blasting them anyways. But if your raid has slows covered, or strong ranged DPS, you can probably skip Chilblains as well.