How does spirit shell work?

Question

In the new Mists of Pandaria patch (5.0.4), Discipline priests receive a new ability called 'Spirit Shell'.

How does this new ability work?

Does it use a cooldown?

When should I use it?

Is there anything else to know about this ability?

Answer 1

The tooltip text for the 'Spirit Shell' ability says:

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Spirit Shell Instant, 1 minute cooldown

For the next 15 sec, your Heal, Flash Heal, Greater Heal, and Prayer of Healing no longer heal but instead create absorption shields that last 15 sec.

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This ability is a temporary self buff which causes any healing done with your Heal, Flash Heal, Greater Heal, and Prayer of Healing ability to cause a Spirit Shell absorption barrier to appear on your target instead of healing them, for the full value of the healing that would have been done.

The Spirit Shell cooldown length is 1 minute, and the Spirit Shell ability does not trigger the global cooldown when it is used, meaning it can be macro'd with other abilities without using a GCD.

The maximum absorption value for Spirit Shell caps out at 60% of your health, and with a balanced stat makeup at level 85 (healthy values of mastery, some critical strike chance, and with full Grace stacks) it is reasonably possible to cap Spirit Shell on a single player with a single Greater Heal cast.

A good time to use this ability is during periods of preparation for large amounts of incoming damage, when the raid group or dungeon group is already at full health. Using this ability will create a new shield on your target that will remain on the target for 15 seconds or until fully absorbed. Recasting additional instances of spirit shell on a target already affected by the spirit shell buff will result in the stack timer being reset and the absorption amount increasing to the sum of it's existing absorption value plus the value of the new spirit shell - for a point of reference, this is the same way that Divine Aegis stacking works.

The calculation for the absorb created by spirit shell is as follows;

Non-POH Shell = Average Heal * (1 + Mastery %) * (1 + Crit %) * (1 + (Crit % * 0.30))

POH Shell = Average Heal * (1 + Mastery %) * (1 + Crit %) * 1.30

As you can see from the above calculations, spirit shell scales in a linear fashion with Crit% in a way that is better than the original spell's (ie: Heal) scaling. Haste does not have a direct influence on an individual cast of Spirit Shell, however it will affect the number of Spirit Shells you can cast while the buff is up. Mastery, of course, affects the size of the absorption effect created per cast.