Originally Posted by seraphthrone

Just did some experiment yesterday in ICC, and I was surprised.

Conventionally, OB seems to be the most hard-hitting/rune efficient spell to cast. And most DW frost DKs center their rotation around OB. However, after I checked my parses yesterday, I observed something quite...interesting:

OB hits for about 1.5 times harder than HB, not as hard as I'd expected.
OB also hits for about 1.5 times harder than FS, same as above.
The rotation is really a fuckfest, with diseases not aligned, runes not aligned, runes pop randomly from RE, etc.
Extreme GCD issues in frost presence, varying from too much free GCD at one time and not enough from another time.
RP is very hard to predict. Sometimes I have no RP to spend and just not doing much and then a few seconds later I got a full RP bar because all the procs just jammed into that one second.

Based on the observations above, I came up with an idea: what if I don't use OB, but instead use HB as my primary attack. This will make things a lot more simpler because HB only cost 1 rune and does no require me waiting on any thing. There are a few things to consider:

OB costs 2 runes and only does 1.5 times the damage HB does. But HB only costs 1 rune.
OB consumes KM, and only does 1.5 times the damage FS does.
FS refreshes new runes with 45% chance, OB procs rime with 45% chance.
RE refreshes runes that ARE ON COOLDOWN, meaning if a rune is not on cooldown, RE will ignore those runes.

With these things in mind, I came up with a priority system based on HB.

Priority:
When both FR are up, cast HB
When both BR(DR) are up, cast HB
When RP is about full, cast FS
When both BR are up, cast BS
Spend rest runes on HB or BS
Spend rest RP on FS
Cast horn

One can see, this system has no PS or OB. You might question: Why no OB? OB cost two runes, generates 20 RP, hits about 1.5 times harder than HB, but requires waiting on the runes to be aligned and consumes KM. HB on the other hand, cost only 1 rune, can be cast anytime, and generates 15 RP, do not consume KM procs. Why no PS? I don't use OB, PS doesn't do much damage. And when UR are on cooldown, RE might refresh that UR instead of FR or BR, which is not desirable. I want my RE to refresh FR or DR(BR) instead.

This system seems really smooth. Several highlights below:
1. HB hits extremely hard for a 1 rune ability, generates more RP than OB. With more RP, that means more FS, which via RE, generates more runes, which, in a cycle, generates even more RP.
2. No GCD issue, PS is avoided and the reservoir of runes and RP is easily controlled, therefore no wasting of resource
3. Utilize mastery to its full extends. Both HB and FS are frost damage. This also frees up a glyph space for frost disease, which is, you guessed it, frost damage.
4. Bypass the armor by avoiding PS and OB. Since we no longer has armor penetration, OB doesn't do as well as it did before even with all the buffs.
5. Of course, this comes with some amazing cleavage aoe damage.

I only used this system for a few fights, and it seems it works quite nicely. Of course at this stage of the game, this system needs more tests and some math in the end to verify its validity.