Seal of Blood is probably the most underrated ability in a Blood Elf Paladin's arsenal, especially where tanking is concerned. I myself was very skeptical of the ability for a long time, but after reading some of Kathryn's posts on these forums and doing some theorycrafting of my own, I was curious. I had the opportunity recently to pick up a King's Defender, and so I started doing some testing and absolutely fell in love with the ability.
Before I begin, let me make note of a few important characteristics of Seal of Blood:
- The proc (35% extra Holy damage dealt) does not benefit from +spell damage, however the judgement does. I'm not sure if it benefits from Sanctity Aura (I would guess not although the wording on Sanctity Aura makes it seem possible). Otherwise, it's identical to Seal of Command in that it can be Dodged, Parried, Blocked, and partially "Resisted" ie: glancing blow.
- The damage done to yourself on melee swings is only 10% of the proc damage, not 10% of total damage as the tooltip indicates. I only do 7-10 damage to myself on each swing. I wouldn't be surprised if this is a bug that gets fixed later on.
- The proc is treated as a second swing. This is a very important part of the ability, as I will explain shortly. Note: As of patch 2.1, this is no longer correct.
Gear Choices
Unlike SoR, which favors "caster" swords such as the ever-faithful Continuum Blade, SoB favors more "traditional" tanking weapons such as King's Defender or The Sun Eater. This is part of the beauty of Seal of Blood - it gives us options in our weapon choice. It lets us look at tanking stats such as defense and stamina first, and worry about holding aggro second. It means we can use the "Warrior" tanking weapons just as well as the "Caster" tanking weapons.
Threat Generation
The biggest drawback to using a warrior-style weapon and Seal of Blood is that you will generate less threat overall. Depending on what weapons you're using you might squeeze out a little bit more threat from your melee swings, but the loss of spell damage means you're doing less threat from your spells and judgements, particularly Consecrate. You probably won't have Judgement of the Crusader up either, so that's lost threat as well. Switching from a Continuum Blade with JotC to a King's Defender with JoL means you'll be losing about 76 threat per second from Consecrate alone. You'll also be dealing less damage from Holy Shield. On many boss fights this isn't a big deal - the DPS is killing adds, moving around, or something else - so you can afford to lose the extra threat. However, on any aggro-sensitive encounter, it's usually better to slap on the ol' Continuum Blade.
So why would I want to use SoB?
Well, with the gear choices that SoB opens up, you can pull more tanking stats - and thus, mitigation - out of your weapon. At this point you'll also be generating more threat with SoB than you would be with SoR. However, that's just the tip of the iceberg. Every swing with Seal of Blood active is essentially two swings as far as procs are concerned - one swing for the white damage, and a second swing for the additional Holy damage. This means that, while using Seal of Blood, your proc-related abilities will trigger twice as often. That means twice as many Seal of Lights, twice as many weapon procs, twice as many Battlemasters... any "chance on hit" now has two chances to proc each swing instead of one.
Note that this doesn't really double the proc chance, per se - if something has a 50% proc rate that doesn't mean SoB will make it proc every swing, it just means you have two chances to hit that 50% each swing. Over an infinite sample, yes, you should see a doubled proc rate, but it's important to recognize the difference between a % chance to proc and a % of total swings.
So, let's look at some math real quick. Assume a 1.6 speed weapon (ie: King's Defender or Sun Eater), and JoL healing for 95 each proc at a 50% proc rate. Without Seal of Blood, and assuming 50% of my weapon swings proc JoL, that's effectively healing me for 47.5 every 1.6 seconds - or 29.7 healing per second. With Seal of Blood up, we double the base number (giving that 100%-but-not-really proc rate) to 95 healing every 1.6 seconds, minus 7-10 (we'll say 9) for the damage dealt to myself from SoB. This gives us 84 healing every 1.6 seconds, or 52.5 healing per second. Not bad at all. Most Priests in my guild have renews ticking for over 600 now (every 3 seconds), or a little over 200 healing per second, so it's worth about 1/4 of a renew on me.
Obviously then you could add in things like Reckoning or, even better, Windfury. Having Windfury active gives me a 20% chance to double that 84 healing, as the extra swing from Windfury will also proc SoB. Ultimately that comes out to 100.8 healing per second with Windfury active. Reckoning is a bit too reliant on mob attack speeds and whatnot to do much math with but it gets pretty crazy.
Keep in mind as well that the healing done is causing threat as though you were casting the heal yourself as well. This healing isn't affected by the Paladin's innate reduced threat, and you'll have Righteous Fury active, so it's worth about 56.4 threat per second (see Kathryn's post below). Doesn't make up for the threat lost from spelldamage, but it certainly helps.
Bottom Line
If you've got the weapon for it, and can afford to lose the extra threat, an SoB+JoL combo gives you so much extra mitigation through healing - and possibly itemization as well - that you should really use it whenever possible. Aggro-sensitive encounters, or encounters where you can't keep JoL up are not good places for SoB. It's not really that great for trash either, especially AOE packs. For any other encounter, however, it really gives us an edge.
Seal of Blood and the 2.1 Patch
Unfortunately, Patch 2.1 nerfed Seal of Blood to no longer treat the bonus damage as a second swing. That means no more double judgement procs. That kind of wrecked a lot of the benefit to using the ability, but it does still allow you a fair amount of leniency in your weapon choices. If you happen to have a weapon with a large amount of tanking stats, and threat isn't too big of a concern, Seal of Blood is still a viable option.
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Me, LOL!
