Dean:

This is really cool, I like the concept a lot.
Thanks for the compliments.

If you say you are confused, I know as a teacher that most other people are confused but didn't mention it.

Celestial Energy Pool:
The celestial energy pool is never spent, it only transforms. If you expend two lunar energy points, they become solar energy points. This means that this mechanic regulates how often you lunar energy spells before you cast a solar energy spell, but not how many you cast.

Incantation Slots:
My intention with incantation slots is that this class be a half-caster (like the paladin or ranger), but refresh their slots on a short rest (like a warlock).
The DMG recommends 2 short rests per day. That means that a level 8 twilight warrior can cast 6 2nd-level spells per day. A paladin can cast 3 2nd-level spells and 4 1st-level spells each day. So they are moderately comparable.

Formless Entity:
The names of both features are an oblique and obnoxious reference to Romeo and Juliet.

Spoiler: Act II, Scene II
Show
ROMEO
Lady, by yonder blessed moon I swear
That tips with silver all these fruit-tree tops --

JULIET
O, swear not by the moon, the inconstant moon,
That monthly changes in her circled orb,
Lest that thy love prove likewise variable.


I hope that answers your questions. If you end up using this homebrew, I'd love to hear how it works in practice.