Haste is beneficial to all strains of DK due to it's impact on rune cooldown alone.
Really eager to see the spreadsheet regarding mastery vs avoidance. I have a funny feeling avoidance will still top off as being the better value versus mastery.
One thing I want to bring up on the mastery:
Anything you do to reduce that incoming damage will reduce the effect of your mastery/DS powers. So, if you pop IBF in anticipation of an incoming hit, the follow-up death strike will be limited due to the reduced damage from IBF.
That in mind, I've kinda taken a look at the survival tools for a blood DK and see it can be broken down into basic tiers as to their value to our survivability and the effectiveness of these abilities. As I see it currently, this is how I'd break these down:
Primary - Always on, high returns/effectiveness
Secondary - Mid to low frequency* with high returns OR high to mid frequency* with moderate to low returns
IBF - high damage reduction
AMS - high damage reduction
Vamp Blood - Improves healer's mana efficiency, BIG VALUE currently
Blade Barrier - with new rune cooldown mechanic, more up-time
Rune Tap - on demand heals for 15% of base health, and can be group heals also
Lichborne/DeathCoil Combo - (see OP)
Tertiary - Low frequency* with mid to low returns
DS - high rune investment, duration short, value as a minor cooldown (regardless of mastery level)
Blood Worms - hard to time, low chance, group heal though
Bone Shield - low to moderate effectiveness, long wait to reuse
(*Frequency = ability's effective uptime)
I've been using this as a "mini-cooldown". BB, HS, and diseases are my bread and butter for maintaining threat in multi-mob situations. DS used mainly on boss fights, spaced out with blade barrier to try and keep some sort of level damage reduction up. It's a little tricky though. The one big benefit I've seen is removing the tie to diseases, as before, in order to get benefit out of DS, it used a FU pair that you might need to refresh diseases. I don't rely on it as much as an offensive, aggro generation device anymore.
Pain here is that it can take away effectiveness of DS blood shields. Good for softening up big hits and buying a little bit of breathing space afterwards for the healers. Seems like most are having issues with mana and my approach has been trying to keep myself from becoming a mana sponge.
Which leads me into....
Best bang for the buck so far. Again, tied into the previous mana sponge notion, it's just needed. If the healer over-extends trying to keep the tank and dps (which, now have health pools of 100k+) topped off, it's easy to find yourselves in trouble quickly. I know it's NOT a tank issue, but my recommendation is that ANY dps with self-heals need to use those if they have them. Rogue's is sweet. DK dps, I'll use death strike to try and reduce workload on healer when I run dps. Pally, Word of Glory. Enh shaman have an instant when they do things right.
Back to avoidance though, I feel that dodge/parry lead the pack for ANY tank, regardless of class, simply due to survival issues. Mastery is nice, but it's not king. Compared to the actual hits we're taking as tanks, blocks from shields of any sort, blood shield or other, is a pittance compared to the gain from avoidance.
Just my two cents.........
No one tanks in a void.........