9thlv spell or epic spell Idea.

[kiryoku]

ok so i have an idea for a spell

negative energy avatar(Evil)
it starts with a burst of negative energy damage i was thinking out to 40ft to 60ft and it would do some where around 6d8 damage.
then you change into a creature of negative energy only
you gain natural attack of 1d8 negative energy claws
and a burst 10ft touch attack every 1d4 rounds that does 4d8 to 6d8
also a line 15ft wide and 60ft to 120ft long it does caster level X 1d8 negative energy but it takes 2 to 4 rounds to charge up

i want it to have fast healing, a Damage reduction, and spell resistance.
some aura that helps undead
but you lose all spell casting and gain elemental, outsider, or undead type i have not made my mind up on that one but i think elemental is closer to the concept. i also i think you become large size and gain str+6 Dex+2 (con+4 if it has one) cha+4 or some where around those ability score bonuses also these are separate from the size gains.

as for how you look
you look like a humanoid shaped negative energy creature with long thin arms with crimson eyes and mouth. the mouth has jagged teeth with no lips. also the face is darker than the rest. maybe with horns or a horn?

[Icewalker]

Sounds fun. Might be more thematically functional as a class capstone than as a spell, but it works. Your numbers sound more or less reasonable, although some of what it can do is a little unorthodox (not much precedent for blasting abilities that take multiple rounds to charge and fire). Seems pretty cool though.

Personally, I'd use an effect like this as a PrC capstone, or as a plot point in a campaign.

[kiryoku]

that sounds cool feel free to use it like that when its done.

and i changed my mind outsider fits it more then elemental.
SR10+1/2 lv+ cha mod
HD DR
17-20 5/-
21-25 10/-
26-30 15/-

caster level = hd so a 18 lv caster would have 18d8 hd +18 BAB +11 on all saves

fast healing
HD healing
17-20 5
21-25 8
26-30 10