A few things I've noticed playing my boomkin in 25 man raids (This is parroting a lot of what has been said earlier, just summarized for convenience):
* Rotation is extremely important. Missing the Eclipse GCD and accidentally procing a wrath eclipse makes a noticable dent in your dps. Wasting GCDs during eclipse for anything except refreshing Moonfire early during the eclipse also means a dps loss. You want to get as many starfires as possible in during those precious seconds. SquawkAndAwe is a must for any serious raiding moonkin.
* Don't gear for crit. At all. Ignore crit gear except for T7. With talents, moonkin form, chaotic skyfire, 4pc T7 and 3 of those 4 T7 pieces, plus raid buffs you still have well over 25% crit, and haste is way better than crit for dps.
* Use Starfall and Treants when possible. On short fights, if possible, ask your shaman(s) to tell you a few seconds before they use bloodlust and treants then, as they benefit from Bloodlust and it's a noticable dps increase if they do. On longer fights just pop them as early as possible so you might get a second use in before the boss dies.
* Use the insect swarm glyph and use Insect Swarm. Don't refresh Insect swarm during Eclipse though. It's not a huge dps increase, but it's still a dps increase.
* Don't be dishearted if your dps varies from one time to another. Eclipse is an RNG ability, and when the numbers are in your favor and you only need to wrath 1-2 times for each eclipse you will see nice and big dps figures, but when the RNG is being a bastard and you have to wrath 10+ times for an eclipse your dps can drop by several hundred. Note that this is still not an argument for gearing crit instead of haste. (Hey, at least it's not Hot Streak..

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