I've been pondering over the datamined Balance Druid talentstoday and wanted to put together a post with my insights in case they end up being helpful for anyone else trying to interpret the changes (or whomever just wants to speculate with me). So far I'm actually really liking what I'm seeing, despite being skeptical when the class preview went up last week. I feel like these talents help get back to the core of what it means to play a Moonkin, which to me is evaluating tradeoffs between multidotting and casting nukes.
This post got away from me a bit so I apologize for the huge wall of text!
Also, standard disclaimer that this is all speculation as Legion is still very far off. I tried not to put too much stock in the exact numbers, and focused more on the intent behind the design assuming that the talents end up well-tuned.
Level 15 Talents
Shooting Stars - Moonfire and Sunfire ticks have a chance to call down a falling star, dealing [21% SP] Arcane damage and generating 5 Astral Power.
So, one of the things I've really liked about what they've shown for Moonkin so far is the lack of any RNG element in our core rotation. As this new version of Shooting Stars is an optional talent, I expect it to be somewhat unpopular seeing as it reintroduces some of that RNG. There are two ways that I see this talent going, depending on how many instances of Moonfire/Sunfire can proc it:
A) If Shooting Stars is capped at one target's worth of dots, as it currently is on live, this is still an improvement over what we have today, because each proc generates only 5 AP, instead of a full charge of Starsurge (equivalent to 40-60 AP). This means the proc chance can be much higher than it is on live, resulting in a more consistent and smooth AP generation. It would need to have comparable AP generation and bonus damage to the other two talents in single target situations, however, meaning that this talent would simply be a playstyle choice - one that most players won't choose due to the lack of control.
B) However, if Shooting Stars can proc from all of your Moonfires/Sunfires, as the description leads me to believe, this could be a lot more attractive in multidot situations. Being able to proc more AP with more targets dotted enables a rotation that focuses on using dots to generate the AP needed to cast Starfall frequently. Similar to Fire and Brimstone AOE, which gets easier to sustain with more targets. It's interesting how much this one talent (if implemented this way) could dramatically change the rotation, as without it, taking the time to apply Moonfire to multiple targets would be a net AP loss, even if it's a net gain to overall DPS.
Starlord - When your Solar and Lunar spells are empowered, their cast time is reduced by 50%.
Besides having the best name of any talent in the new trees, this seems so good that it's too good to be true. I would really be shocked if this made it live as a 50% reduction. This talent synergizes speeds up the whole rotation dramatically - Faster Empowered LS/SW -> Faster AP generation -> More Starsurge -> More Empowered LS/SW, which you can cast faster! If it weren't good enough on its own, it combos incredibly well with some of the other talents lower in the tree, which I'll discuss below. Then there's also the QoL aspect where we won't need to hardcast as many 2.5s Lunar Strikes. There really is little to not like about this talent - it's basically Euphoria on steroids.
Warrior of Elune - 45 second cooldown. Your next 2 Lunar Strikes have no cast time.
A nice little talent, which will probably not be in the default build, as saving two seconds of casting every 45 seconds isn't much of a DPS gain when standing still. I think this will see situational usage on fights where you can pop it and fire off two LS during a raid move, and 45 seconds is short enough that this could line up with a lot of major raid mechanics.
Level 30 Talents - Nothing really new here, skipping this row
Level 45 Talents - Affinity Row
This seems like it could end up being an idea that is interesting in theory but doesn't really work out in practice. I assume most raiders will take Guardian for the passive damage reduction. The passive healing doesn't seem that great, and the movement speed is nice but inferior to Displacer Beast. As for the active abilities, it appears that you get all the core rotational abilities of the other specs, but none of the cooldowns or talents from that spec. That feels like you'd still be a considerably weaker version of that spec, though it depends heavily on tuning. The best scenario I can think of are those fights where you want to bring a 3rd tank in Phase 3, for instance, but not have them do mediocre DPS in Phases 1 and 2. Even then, I think it would make more sense to bring a Bear who has DPS affinity than a DPS who has Bear affinity for this role.
Level 60 Talents - Nothing really new here, skipping this row
Level 75 Talents
Stellar Flare - Burns the target for [39% SP] Spellstorm damage, and then an additional (156% of Spell power) damage over 24 sec.
Stellar Flare benefits from both Lunar and Solar Empowerments, consuming 1 of each.
I'm cautiously optimistic that this talent doesn't suck anymore. With Moonfire's duration being reduced to 12 seconds and Sunfire's down to 8, this spell has the distinction of being our longest duration dot by far, making it easier to maintain on multiple targets. There's also the possibility of interesting variations in a StFl rotation depending on number of targets and whether they are grouped, because you *can* but don't *need* to use Lunar/Solar Empowerments to cast it. For instance, on three grouped targets, it might be optimal to spend your Lunar Empowerments on LS but put your Solar Empowerments into StFl so that you never need to cast SW. I'm also curious whether this is going to have a cast time as it does on live - the WoWHead datamining is showing this spell as Instant but it's also doing so for LS and SW so I'm hesitant to trust it at this point.
Incarnation - 3 minute cooldown. An improved Moonkin Form that increases all your spell damage by an additional 15%. Lasts 30 sec. You may shapeshift in and out of this improved Moonkin Form for its duration.
Not a whole lot to say here since this is unchanged from live. This being a talent automatically attaches the stipulation "But you have to give up Incarnation to get it" to both of the other talents in its row, because of the ridiculous burst you can get when stacking it with Hero/CA/Pot/Trinkets/etc. The other two talents *have* to be potent enough to offset this effect with sustained damage, or they're dead in the water. It also works just as well no matter how many targets you are attacking, something that can't be said about the other two.
Soul of the Forest - Increases the damage bonus from Lunar and Solar Empowerment by an additional 15%.
This talent is also just as boring as it is on live, but could work out to be better overall damage than Incarnation in a Single Target Max AP Generation build, as detailed below. Then it just comes down to whether the fight calls for heavy burst or sustained damage.
Level 90 Talents
Stellar Drift - Increases the radius of Starfall by 30%, and the damage dealt by 20%. Additionally, while you are inside the Starfall you can cast while moving.
Finally, a talent that improves Starfall! My impression is that the bonus damage isn't the reason you would decide to take this talent, because at 60 AP/8 seconds it's going to be hard to maintain high uptime without a lot of haste. Instead you would pick this up on fights where you need to be able to AOE a large area - Kromog for example - or on fights that are so movement intensive that Starfall becomes a mini cast-while-moving cooldown that also happens to deal damage.
Full Moon - The damage dealt to the primary target of Lunar Strike is increased by 25%.
I believe this is actually a multi-target talent that's pretending to be a single-target talent. Reason being that, at current numbers, SW is the filler on single target, SW=LS on two grouped targets, and LS is the filler on 3+. In other words, you won't be using LS enough on single target for its +25% damage to be worth it. Meanwhile, the case where this talent shines is when you are already cleaving and want to do more damage to your priority target - which is often the case when adds spawn.
Nature's Balance - Your Lunar Strikes extend the duration of Moonfire by 6 sec. Your Solar Wraths extend the duration of Sunfire by 4 sec.
At first when I saw this talent I groaned, as I'd never been a fan of the dot extending gameplay of BoP on live. But then I realized that this is a far better version because of the reduction to Moonfire and Sunfire's durations. It takes 4 GCDs/minute to maintain 100% uptime on both dots for a single target currently - with the new durations this will instead take 12.5 GCDs/minute. Furthermore, I believe that Sunfire's DPET will be tuned such that it is only worth casting if you can hit 2+ targets (possibly even 3+), or if you are on the move and have nothing better to cast. That's where this talent comes in. With Nature's Balance you can maintain both dots indefinitely, saving the GCDs needed to apply them and getting the benefit of Sunfire's periodic damage in a situation where you might not even apply it at all. Unfortunately since it still takes a lot of effort to maintain both dots, this won't see use outside of fights that are primarily single target.
Level 100 Talents
Collapsing Stars - 2 minute cooldown. Burns the target for [1000% SP] Spellstorm damage, and then an additional [400% SP] damage per second until your Astral Power is exhausted. Replaces Celestial Alignment.
I really want to love this talent for its insane burst potential, but its 2 minute cooldown doesn't sync well with Incarnation's 3 minute cooldown. There are enough different burst talents that you'll have the flexibility to take whichever combination of cooldowns lines up best with what the fight needs. I'm assuming based on how this is worded that it will not be channeled, but place a dot on your target which will attempt to drain 10 AP from you every second and deal damage, and when your AP hits 0 the dot falls off. Implying that you could continue to cast while CS is active, the goal would be to get to 100 AP, have Moonfire applied and possibly several Empowerment charges saved up, then pop CS and hard cast AP generators to keep it going as long as possible. This seems like it could be a fun and rewarding playstyle, compared to fire-and-forget CDs like Incarnation.
Blessing of the Ancients - Gain a Blessing of the Ancients, activating or swapping between one of the two following beneficial effects: Blessing of Elune Increases Astral Power generated by Solar Wrath and Lunar Strike by 50%. Blessing of An'she Grants 3 Astral Power every 2 sec.
Interesting design here as this is really two talents rolled into one, that you can switch between on the fly. The AP generation from Blessing of Elune is massive as long as you can turret and you're not spending too much time multidotting. Meanwhile Blessing of An'she generates slightly more AP than Astral Communion at 90/min, but it comes at a slow trickle instead of all at once, and feels to me like a stance you would go into if you had to stop DPS, or wanted to go with a dot-heavy rotation and didn't need the burst potential.
Astral Communion - 1 minute cooldown. Generate 75 Astral Power.
A simple, minor burst cooldown. At 0 AP, you can pop this then cast SS -> Emp LS -> Emp SW -> repeat four times in a row without running out of AP, for some above average damage. It also lines up well with CA+Inc and helps get the rotation going if used in the opener (whereas without it, you would need to cast a few unempowered builders before firing off your first SS). Even though this generates less AP/min than Blessing of An'she, comboing it into other cooldowns probably makes up enough for this fact. It's also useful regardless of the number of targets.
Conclusion and Possible Builds
So I've alluded to it multiple times above, but there are so many talents that work together in interesting ways. Let's start by looking at what I think will be the Max AP or "Target Dummy" build:
Talents: Starlord + SotF + NB + BotA. Rotation: MF > SuF > SS > E SW > E LS > SW.
Starlord and BotA combine to produce absurd amounts of AP - The bonus from BotA means you are casting unempowered builders less often (as E SW + E LS = 36 AP, almost a full SS), Starlord makes all of those empowered builders faster, and the result is that you can cast a SS approximately every 4 seconds, without even counting for haste! Then just for fun, throw in SotF to make all of those empowered builders do 15% more damage, and NB so you only need to cast MF/SuF once and get all that damage for free. This already feels like a really good build, albeit a bit boring, though the math hinges on Starlord not getting nerfed, so don't count on that too much. But there aren't that many true target dummy fights, so let's look at what we might swap in.
2-3 target sustained cleave:
Talents: Starlord + StFl + FM + BotA. Rotation: MF > SuF (maybe?) > SS > E LS > StFl (uses Solar Emp.) > LS.
The Starlord + BotA combo is still too good to pass up here, but we've had to drop NB and pick up FM instead as we can't maintain dots on both targets, and we've switched to LS as filler anyway. StFl also makes its way in as it's worth more when we can multidot with it, and the DPET bonus from using the Solar Empowerment charge is theoretically better than using SW. This build also works if there are additional low-priority targets in the clump that can be passively cleaved down with LS and SuF.
4+ target sustained AOE:
Talents: ShSt + Inc + FM/SD + Any. Rotation: SuF > MF > Starfall > LS
Things get a bit nebulous out here without actual numbers. How many targets is enough for Shooting Stars to sustain a high Starfall uptime? Starfall works best when most/all of the targets it's hitting are dotted, because it improves MF/SuF damage by 30% (plus mastery?), though not StFl, so we turn to Inc as the only thing left in the row that works. If there are priority targets, you might decide to stick with Starsurge, but then you have to decide whether to cast SW or let the Solar Empowerments go to waste, and that rotation could a bit bogged down trying to keep up Moonfires. It seems possible that there could be a "sink" at the low end of this target count, where there are not enough targets for you ShSt to generate enough AP on its own, but too many targets for you to keep everything dotted and still generate enough AP through LS.
Burst Options:
Biggest burst every 4 min, mostly single target: CS + Inc
Big burst phases every 3 min, ST or AOE: CA + Inc + AC
CS or AC can also be taken without Inc for moderate burst more often
Mobility Options: Both WoE and SD offer increased mobility, possibly at the expense of some throughput.
All of this is of course pure speculation and subject to change, but I hope you found this useful and would love to hear your thoughts!