7.5. Survival Abilities
As a Protection Warrior, you have two abilites that are essential to staying alive: Shield Block Icon Shield Block and Shield Barrier Icon Shield Barrier. In the following sections, we will tell you everything you need to know about them. Then, we will explain when it is best to use one over the other.
7.5.1. Shield Block
Shield Block Icon Shield Block grants you a 6-second buff that causes you to block all incoming attacks. It does not have a cooldown. Instead, it works on a system of charges. Each charge has a 12-second recharge time, and you can have a maximum of 2 charges.
You can use Shield Block twice in a row (provided that you have enough Rage) without wasting any part of it. Indeed, using Shield Block while the buff from a previous Shield Block is still active will simply add their durations together. For example, if you use Shield Block when you had 3 seconds left on a Shield Block buff, your new buff will have a 9 second duration.
Shield Block has a high Rage cost of 60, so you must learn to use it wisely. To know how to best use Shield Block, you must understand what it is and what it is not effective against.
Shield Block works against physical attacks, but it does nothing against magic attacks (spells cast at you, AoE spells, DoTs).
Shield Block does not work against all physical attacks. Some attacks, such as specific encounter mechanics (Impale-style abilities), and abilities that apply bleeds cannot be blocked.
Shield Block is particularly useful when you are being attacked by multiple targets.
What all this means is that you want to use Shield Block to mitigate powerful boss melee attacks. If the boss you are fighting attacks in a steady and predictable manner, then using Shield Block is easy. If, however, the boss sometimes attacks faster or harder (going into a Frenzy), then you need to have Rage in reserve so that you can use Shield Block at the appropriate times.
7.5.2. Shield Barrier
Shield Barrier Icon Shield Barrier places a damage absorption shield on you, which absorbs an amount of damage (based on and scaling with your attack power). Shield Barrier has a 1.5 second cooldown, and it costs 20 Rage. However, if you have more than 20 Rage, then Shield Barrier will consume up to a total of 60 Rage. Any additional Rage past 20 will increase the amount of damage absorption that it provides.
Unlike Shield Block, Shield Barrier does not stack with itself. In fact, you cannot cast Shield Barrier while a previous Shield Barrier buff is already active, unless the amount of damage absorption of your new Shield Barrier is greater than the remaining damage absorption of your old one.
The absorption effect lasts for 6 seconds, but in practice it will almost always expire within the first one or two attacks you receive.
Also unlike Shield Block, Shield Barrier works against all types of damage (excluding fall damage).
7.5.3. Shield Block or Shield Barrier?
Due to their exorbitant Rage costs, Shield Block Icon Shield Block and Shield Barrier Icon Shield Barrier are practically mutually exclusive. In any case, this is not a problem, since every situation is always ideally suited to one of them, but never to both.
The amount of damage that Shield Block mitigates is based on the power of the attacks it is mitigating. Blocked attacks have 30% of their damage reduced (60% of it is reduced if your Mastery, Mastery: Critical Block Icon Mastery: Critical Block, procs). Therefore, a very powerful attack will result in a much greater damage reduction from Shield Block than a weak attack will.
On the other hand, the damage absorption of Shield Barrier is independent of the incoming damage. Shield Barrier will absorb the same amount of damage, regardless of whether the attack made against you deals 10,000 or 100,000 damage.
Therefore, when deciding which of the two abilities is better to use against blockable attacks, you need to look at which of the following two values is greater:
The absorption amount provided by Shield Barrier.
30% of the attacks received over 6 seconds.
When facing magic damage, bleed damage, or otherwise unblockable damage, Shield Barrier is the superior choice.