Re: Mastering the Elements [3.5, Invocations]
Sandstorm Blast is too powerful for a Lesser: it's at least a Greater invocation. It just outclasses everything at its current level and some of the Greater ones.
Shield of the Depths i'm not sure about. I'd say it was lesser if you just restored it as a Standard action [like other, similar Invocations]. I'm never sure about fast healing as a feature: it's often barely worth it.
Sing the Winds seems a little excessive for even a Dark power. If it were a normal Control Weather it would probably be fine. Not that there's all that much you can do with it, in combat at least.
Water Blast uninspiring name. Hydraulic blast? I'd allow it to knock the victim back somehow, but that's just me. Admittedly, it would probably be Lesser then. It should be able to put out fires and probably be used to counter Fire spells below a certain level, given that it's a hose...
All the rest look fine. I like Ward Torch especially.
Mine is not so much a Peter Pan Complex
as a Peter Pan Doom Fortress and Underground LairTM
Want a fae from folklore stated? Give me the lore and I'll do it for you!
Le Cirque Funeste
Evil Fairy Circus! Ray Bradbury, refined down to snortable powder!