Yes, Dragons were surprisingly good for disc.
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The problem with this is that our artefact ability's and the boss abilities' cooldowns are multiples of the the same high number, so the time span between the damage incident and our heal will gradually become bigger and other healers will snipe us when we try to use it as soon as possible. (This happened to me a lot on Ursoc.)
Especially when they rotate CDs. We could just ask them to count us as a "raid cd" with a very short CD, but for one they that would mean they get less healing on the meters and, two, there is much more that can go wrong with the setup of our buff and damage combination than there is for other raid CDs.
Those debuffs every encounter seems to have where you have to run somewhere absolutely kill our Atonement setup if we get them.