Boss specific recommendations and strategy:Raid Bosses
Tier 1 (15)
Blooddrinker drains a decent amount of health from your target over 3s with a 30s cooldown. Rune Tap, Anti-Magic Shell, Vampiric Blood, Dancing Rune Weapon and Icebound Fortitude can all be cast while channeling.
Tombstone consumes up to 5 Bone Shield charges to grant 30 runic power and an absorb for 30% max hp for 8s on a 1 min cooldown.
Once you acquire the tier set and Crimson Rune Weapon legendary you should use Tombstone in all forms of content, as the 25s reduced cooldown on Dancing Rune Weapon (due to the interaction with Crimson Rune Weapon) is tremendously powerful.
Tier 2 (25)
Rapid Decomposition: causes Death and Decay and Blood Plague to tick 15% faster while keeping their original duration. This leads to more damage and healing as well as Blood Plague doing 50% more damage.
Hemostasis: increases the total damage and healing of your next Death Strike by 8% for each target hit by Blood Boil. The effect has a 5 stack cap which means the maximum gain from this talent is 40%.
Consumption: is a melee cleave that has a target cap of 8. The ability itself does decent damage and heals you based on the damage dealt.
For this row, Hemostasis is the only viable option as it provides the highest offensive and defensive benefits of the 3 options in both AoE and single target scenarios.
Tier 3 (30)
Blood Tap: is an active ability with 2 charges. The ability itself is off the global cooldown and you regenerate the rune with the longest amount of time left. Additionally, when you lose a stack of Bone Shield, Blood Tap has its cooldown reduced by 2 seconds.
If you are just picking up the spec then you could opt to run Foul Bulwark until your are more comfortable with rune management
Tier 4 (35)
Will of the Necropolis: absorbs 30% of all damage you take when you fall below 30% health. Furthermore, the damage is calculated based on any damage that brings you below 30% so if you are at 50% health and a hit takes you down to 20% health then 10% of that hit will have the 30% damage reduction applied to it. It is a really nice talent to have and adds more of a safety net to the class when you are taking heavy damage.
Mark of Blood: debuffs your target for 15 seconds which makes them heal their target by 3% of their maximum health every melee swing.
Will of the Necropolis should be your default choice in all content as it is the most consistent and reliable damage reduction in the tier. Anti-Magic Barrier has some niche applications on specific fights. Mark of Blood is extremely under-tuned and should never be picked.
Tier 5 (40)
Grip of the Dead: applies a 90% slow to enemies when they first enter your Death and Decay decreasing by 10% every second.
Wraith Walk: is a 1-minute cooldown that increases your movement speed by 70% for 4 seconds, though any spells cast during this time will cancel the ability. This will also break any roots affecting you when cast.
Grip of the Dead is one of the most powerful aoe slows in the game and is very useful whenever you want to kite or stop adds from moving. Tightening Grasp is a niche talent, but can be very powerful on certain raid fights (such as Anduin). Wraith Walk is always a welcome addition to a low mobility class like DK whenever movement is required.
Tier 6 (45)
Voracious: increases the healing Death Strike does by 20% and grants you a 15% leech buff for 8 seconds whenever you Death Strike. Additionally, the minimum healing of Death Strike is increased to 10.5% from 8.5%.
Death Pact: instantly heals you for 50% of your max HP, but then puts a healing absorb on you for 30% max health.
Bloodworms: have a chance to spawn small worms from your auto attacks which attack your main target for 15 seconds. After those 15 seconds or if you fall below 50% health, the Bloodworm will pop and heal you for 15% of your missing health.
In any form of challenging content the added healing from Voracious will be the strongest option in this tier.
Bloodworms can be taken if your damage taken is not threatening and you want to maximise dps output.
Tier 7 (50)
Purgatory: is Blood Death Knight's cheat death ability, which is very strong when learning a new fight. When you are struck by a killing blow you are instead shielded with a heal absorb for 3 seconds which if is still prevalent when it expires will kill you. However, if you heal up the absorb, you will return to life. You are unkillable during these 3 seconds.
Red Thirst: reduces the cooldown of Vampiric Blood by 1.5 second for every 10 runic power you spend.
Bonestorm: is an AoE active ability with a 1-minute cooldown. The ability can be used with anywhere from 10 to 100 runic power and its duration is based on how much runic power is spent up to 10s. You are healed for 3% of your maximum health for each target hit, up to a cap of 15% per tick.
Purgatory should be your default choice whenever you’re in danger of dying while doing harder content, as the strength of a cheat death cannot be understated.
Red Thirst allows for much better cooldown planning and usage throughout a fight, and is the talent of choice if you’re running a cheat death trinket.