Phantasmal killer in earlier ed like pathfinder is a one shot kill if the opponent fails 2 checks, from my memory its wisdom and constitution. Weird is an aoe version. When I played with my friends as a DM I homebrewed the spell into the following.
Phantasmal Maim: [level 4]: target takes 10d6 if they fail a DC [15], on save take half. On failed save, frighten enemies in 5m radius around target. Target takes 1d3 for 1d3 rounds.
Phantasmal Force: [level 1]: deal 1d4 damage up to 3 enemies for 1d3 turns- if cast with concentration deal 2d4 up to 4, [dc 10 con save], save nullifies
Phantasmal Killer: [level 5]: Attempt a constitution check, if yours is higher, opponent takes 20d4 damage, if they die, cast again if pass a DC 20 wisdom check.
Weird: [level 8]: Deal 20d4 damage in a 20M radius around yourself, you must pass enemy save+ level + prof, versus your roll + level + prof. If all hit targets die, make a dc 20 check on wisdom, to cast again
