Forgive the vulgarity but the save or die spell formula sucks. This is not to say I think the death save needs to be removed from those spells (it doesn't) because they're countered by an easily available array of anti-death / relevant immunity due to rightful understanding of counters.
I don't think that needs to change either. DC based spells are also pretty bad design in so far as "save or something" without anything else just feels like a waste because it is. I am not really going to go there though because I specifically think the Save or Die spells need a reshuffle in order to be relevant again.
The Phantasmal Killer & Weird spells are not great. Everyone is fear immune, mind immune, and so are most monsters.
Suggestion(s):
* Make it always do a direct damage regardless of save fail or immunities as long as the entity is living or intelligent undead/constructs. PK should do about 10d6, Weird 20d6. (Metamagic only effects this dmg, not additional dmg).
* If you fail the save v fear it does more damage, fear immunity halves this roll and stops progression to death save. Both receive 5d6 more damage.
* With the fear effect active - you will however take an additional 1d6 a round you are feared.
* If you fail the save v fortitude you die, if you are immune to dying, it just does another 5d6 more damage.
* Specific to Weird: Kind of a bug/maybe just aged game stuff. It requires you to be way too close to cast and has a delay that gets worse during lag. Just make Weird into a spell like shadow bolt or firebrand where it selects targets (1) per caster level. If not - please just make the spell function faster.
* Ablosh weird's "HD" caveat. Let the younglings have the honor of rolling a 20.
* Make /intelligent/ undead, undead PCs, intelligent constructs, elementals, and the like also be affected by these spells - even though DnD makes this part of their superpower - it puts Illusion in the boat of "worse enchantment", and since these kinds of creatures have minds and eyes you can trick.. why not also with magic?
Disintegrate is great.
Circle of Death, Finger of Death, and Wail of the Banshee are the iconic necromancy spells. They are also awful due to immunity availability and a lack of anything else.
Suggestion(s):
* Give each appropriate amounts of damage that happens regardless of saves or immunities. Circle of Death should become a scaling 10d6 negative energy spell. Finger of Death should literally just become a negative energy Disintegrate with 40d3 dmg, and Wail of the Banshee should do a mixture of 12d6 sonic and 8d6 negative dmg. Meta magics apply here.
* Failure of their fort saves should still result in death - but immunity provides an additional amount of damage if they failed the save. If FoD is more like a Disintegrate (which in my opinion is a good save or die spell already) - probably don't need to add anything. Wail should deafen the caster - but this deafness status comes with a lingering 1d6 negative and sonic damage that remains until the deafness is removed - as some sort of haunting evil tinitus.
* Deeply consider removing CoD weird "hit die" expansion. As much as it seems like its cool for all the necro stuff it just sort of ruins anyone else who wants to do necromancy and not be Skeletor or a cleric.
Destruction is a pretty cool spell but its old. My only suggestion is make it match Disintegrate/FoD but do divine damage instead and also make it do damage regardless of death immunity.
Nybor's Wrathful Castigation is also kinda like the Phantasms. Not really viable or valid with the immunities. Honestly this one I don't know how to flavor that well as I do not vibe with it. Enchantment is a pretty powerful school in the current meta.
Suggestions:
* Scales sort of like harm but caps at like 80 damage.
* Mind immunity halves that damage.
* Willsave if no immunity, get daze like normal.
* If you get a daze, roll fort for a death. If immune to death spells do a lingering 1d6 dmg until clarity/mind immunity is applied.
thanks for coming to my "save and its a dud" tedtalk for some of the iconic spells no one really uses anymore