Patch 22.0 Card Effect Priority Update
Blizzard just posted about how they changed how Card Effect priority works. It should in theory be more unified now, but there's always exceptions and perhaps there are still things that do not work like you would expect. Blizzard would love to hear about those instances!
Quote from Blizzard
With Patch 22.0, we did a sweeping review in order to bring more cards into alignment with the general rules about priority order when card effects conflict with each other. That general order is the same as before:
Cards referencing their own properties (e.g. Eye Beam) take priority over cards referencing other cards’ properties continuously (e.g. Taintheart Tormenter), which then take priority over cards referencing other cards’ properties in a single instance (e.g. Freezing Trap).
For many cards, this review resulted in no changes—they either had no overlapping effects, or their effects were already working in this way. For example: Lady Anacondra is a card that continuously references other cards’ properties (second category), so it should further reduce costs after Celestial Alignment, a single instance reference (third category).
We’ve also updated a few cards and how they resolve damage. For some cards, this will end up with a different result than before. For example: Moonfang is a card that references its own properties, while Mo'arg Artificer is a card that continuously references other cards’ properties, so now Moonfang will take 1 damage from spells, even when doubled by Mo’arg.
When cards in the same category interact with each other, then priority is based on the order the cards are played, with later cards applying on top of earlier cards.
As with many sweeping changes, we have also seen a few bugs that we’re working on smoothing out (including that Lady Anacondra – Celestial Alignment interaction, the hotfix for which is going out now). As always, there may also be some special cases where certain cards break the general rules so that they can work as intended. We encourage you to continue to let us know if a specific card interaction doesn’t match what’s expected.