As you may have noticed, the most recent update to the patch notes included the removal of the Active Mana Regeneration, and I'd like to take a moment to explain that a bit.
First, I'd like to dispel some misconceptions about what Active Mana Regeneration was. Due to the similar name, and how it had its own section in the patch notes, some people were under the impression that it was as significant a feature as Active Mitigation was for tanks; that was not the case. It was quite minor in its impact. We found, based on internal testing, that in order to make it impactful, we'd have to make it much, *much* stronger. As it was, most forms of it were only worth using when you had mismanaged your Mana and were trying to recover. Based on its low and unintuitive usage, we decided to remove it.
Now, a fair question to ask is, “Why not just tune it stronger, so it *is* worth using?” We considered that heavily. There is probably a design where most of your Mana regeneration comes from active sources, and all healers spend a significant portion of their time and ability usage actively regenerating their Mana. However, that is a gigantic change to healer gameplay, for all healers. Many existing healers would not enjoy that style of gameplay, and we're not even sure that it'd be better gameplay for a new player anyway. Overall, we think that, while that option does seem like it could potentially function, it would not be good for the game.
So where does that leave healers for Mana management? Rest assured, healers will still have significant control over their Mana. The primary method for doing that is through spell selection. We've tuned healers such that they have a mixture of high efficiency and high throughput heals. If you maximize efficiency, you’ll actually be spending less than you regenerate (as of about blue dungeon gear), so your Mana bar will actually be going up. The way you’ll spend that Mana is through high throughput heals, which will let you burn more mana for more throughput. As your gear improves, you'll get more and more Spirit, so that your Mana refills faster while casting efficient heals. And that additional Mana will translate into more and more of your spell casts being high throughput ones, as you get better gear. The key, as it relates to Active Mana Regeneration, is that if you find yourself at 30% Mana, and the boss is still at 50% health, you do have something to do to catch up: lean more on your efficient heals, until you catch up. You'll never end up in a situation where you run OOM and are unable to cast anything. Also important to note, all healers have some way to deal minor damage with no Mana cost now, so that they have something to do when there is no healing needed, if you're the type of player that feels compelled to always be casting something.