if you follow basic rune power generation then, you only have to do this.

i use focus based system so

/assist focus
/castsequence reset=combat icy touch, plague strike, blood strike, blood strike, obliterate, frost strike, frost strike, obliterate, icy touch, plague strike, obliterate, frost strike, frost strike, frost strike

this should essentially give you a frost strike dump automatically, tho you arent using howling blast anywhere, it can be substituted for obliterate, then the third obliterate again, if you wish. Thats the lazy mans way to do it

i prefer this way tho,

icy, plague, blood strike, pestilence, howling blast, frost strike, hungering cold, oblit blood boil blood boil howling blast frost strike frost strike. <-- this sequence would be your ideal aoe nuke, depending on what talents you have to gain death runes. i use a two handed blood/frost spec on my dk's

armory moocrewc on azgalor server t to see the spec i use for all my dks

( i use this sequence for aoe packs)