If I'm not mistaken - and I probably am - it ALMOST looks like Lunar Shower is no longer being used as a buff to DPS while moving. Instead, it simply causes Moonfire/Sunfire to stack increasing amounts of damage by being cast whether you're moving or not, and balances that by making it move your Eclipse bar.

The latter part of the statement implies that instead of hitting Solar Eclipse and staying there spamming Sunfire and Insect Swarm and Wild Mushroom during AOE phases or in PVP, you must cast the off-Eclipse attack that will not move the bar if you wish to sustain Eclipse.

i.e., you enter Solar Eclipse and gain Sunfire. 3 Sunfires will stack to ludicrous damage, but will also generate 24 Lunar energy, moving you slowly out of Solar Eclipse. Wrath or Starsurge will also move the bar, so if you wanted to sustain the Solar Eclipse - say, for a phase change on a boss with an AOE component, like the black vial phase on h. Maloriak, you would instead cast Starfire since that won't provide Lunar energy.