Phantasmal killer (4th-level) and weird (9th-level) have the same effect, with the only differences being the level and that weird affects all creatures in a 30 ft sphere, and phantasmal killer affects a single target:
You tap into the nightmares of a creature you can see within range and create an illusory manifestation of its deepest fears, visible only to that creature. The target must make a Wisdom saving throw. On a failed save, the target becomes frightened for the duration. At the end of each of the target's turns before the spell ends, the target must succeed on a Wisdom saving throw or take 4d10 psychic damage. On a successful save, the spell ends.
Drawing on the deepest fears of a group of creatures, you create illusory creatures in their minds, visible only to them. Each creature in a 30-foot-radius sphere centered on a point of your choice within range must make a Wisdom saving throw. On a failed save, a creature becomes frightened for the duration. The illusion calls on the creature's deepest fears, manifesting its worst nightmares as an implacable threat. At the end of each of the frightened creature's turns, it must succeed on a Wisdom saving throw or take 4d10 psychic damage. On a successful save, the spell ends for that creature.
As we often do with homebrew spell reviews asking "what level should this homebrew spell be?", I'd like to see an analysis of weird in relation to phantasmal killer and other spells. To me, it seems grossly underpowered compared to other 9th-level spells, with psychic scream being a particularly apt comparison:
You unleash the power of your mind to blast the intellect of up to ten creatures of your choice that you can see within range. Creatures that have an Intelligence score of 2 or lower are unaffected.
Each target must make an Intelligence saving throw. On a failed save, a target takes 14d6 psychic damage and is stunned. On a successful save, a target takes half as much damage and isn’t stunned. If a target is killed by this damage, its head explodes, assuming it has one.
A stunned target can make an Intelligence saving throw at the end of each of its turns. On a successful save, the stunning effect ends.
Stunned is much more powerful than frightened (in my estimation), and it takes three saving throw failures against weird to approach the damage of one saving throw failure against psychic scream (8d10 ≈ 44 for three failure to weird, 14d6 ≈ 49 for one failures to psychic scream, which also deals half on a successful save), and psychic scream affects a larger area.
Maybe I'm missing something about the utility of frightening a large group of creatures, but weird just seems like complete trash for a 9th level slot. Is adding the area of effect to phantasmal killer really enough to take it from 4th to 9th level? And if not, what level should weird really be, to be balanced relative to other spells?