Switching to blood presence just for a single frost strike crit is a bad deal.
As Frost dk u need unholy presence even more than a UH dk. Ur whole burst dmg is based on frost strike spam and the reduced GCD from unholy presence is essential for that.
Deathchill should almost always be used with Blood presence infact. Add in Unbreakable armor and Merciless Combat.
Merciless Combat (+12% dmg on under 35% hp) and Blood presence stack, so you can utilize blood presence + deathchill + UA macro to finish people off (should be used to specificly finish them off, but you can also scare people by critting them 8k at 15k hp).
Deathchill should almost always be used with Blood presence infact. Add in Unbreakable armor and Merciless Combat.
Merciless Combat (+12% dmg on under 35% hp) and Blood presence stack, so you can utilize blood presence + deathchill + UA macro to finish people off (should be used to specificly finish them off, but you can also scare people by critting them 8k at 15k hp).
Unbreakable armor and Merciless Combat increase also ur FS dmg while in unholy presence.
I dont see the point to switch to blood presence just to increase the dmg of a single frost strike by 15% unless u can land a guarantee kill with it.
I used to think the same about blood presence everywhere on all specs including blood spec with improved blood presence 10% bonus healing,but noticed... a dk who uses unholy presence or frost will always underperforme the blood presence user vs any class and even dk vs dk.
I mean seriusly lol,frost presence and unholy presence should be used instead of blood,blood doesn't help you vs any class.
Thought it's just an opinion and the way i play,but if you think about it,blood sucks comparing to other presences in bgs and arenas,specially in duels.