Pax said:
Actually, you can get that miss chance with Blink (3d level) and Improved Blink (5th level, from UE). Ghostform was reasonable at a strong 5th level spell. It MIGHT have been okay at 6th ... as a somewhat weak 6th level spell.
With the crit-immunity, I do believe 7th level is reasonable (it'd be slightly strong there, but, I don't really think it's good enough to peg as 8th level).
But both of those spells apply a chance for your attacks to fail as well. Ghostform has no such penalty.
And that's not counting the capability to drift through objects, pop in and out of walls and/or the ground, fly over obstacles or out of reach, and gain a possible spellcasting stat to your armor class. This spell can make a sorcerer into the ultimate mobile firing platform.
Imagine the horror of a shielded, mage armor'd, extremely high charisma sorcerer who has better AC than the warrior, better mobility than the rogue, and a better chance to avoid spells (50% miss chance + normal saving throw) than the monk. He can float around casting spells, hiding in walls when the heat is on, they are soundless unless they want to make sound, the have no physical bodies to trigger blindsight or tremorscense, they have no scent, etc. all with no impact to his offensive capabilities save the ability to make magical touch attacks.
It was the premier defensive spell for sorcerers in my world until we bumped it up. That was before it granted greater fortification to prevent critical hits, sneak attack damage, wounding damage, crippling strike, stunning attacks, and all the other things critical immunity protects a creature from.
Additionally, there is a huge difference between Etheral and Incorporeal. And for a spellcaster (which you are if you're casting Ghostform presumably), Incorporeal is better in every instance.
See this excellent analysis by Sean K. Reynolds.
The Difference between Incorporeal and Ethereal
Our original fix was to swap etherealness with ghostform in levels and lower ethereal jaunt. Now that ghostform is even more powerful I'm not sure what we are going to with it and arcana form.