What level should this version of Warp Mind be?

Question

I have taken this spell from Pathfinder 2e, where it is a level 7 spell (I think here are 10 levels there though), and converted it into a 5e spell.

I think it is still around the correct power level for a 7th level spell, but just putting this here to get some alternative opinions.

Warp Mind: 7th(?) level enchantment

Casting time: 1 action

Range: 120ft

Components: I don't care

Duration: Instantaneous

Effects: Fluff, blah, blah. The target takes 4d6 damage and must make an intelligence saving throw. On a successful save it suffers no additional ill effects and the spell ends. On a failed save it suffers the effects of the confusion spell.

At the end of every 30 days the creature can repeat its saving throw against the spell. If it succeeds the spell ends. The spell can also be ended by a greater restoration, heal or a wish.

My reasoning:

This spell is a bit like Feeblemind deliberately, but has a clearly less harmful effect. Therefore it should be lower level than Feeblemind, which means 7 or lower.

I don't think there are any other similar spells in terms of length of effect, and while the confusion effect is (imo) a generally poor one for combat I think the sheer length of time means this has to be a high level. Hence I think it should be level 7.

Geas might be similar, but has effectively no combat use, so that probably puts a lower bound of 5th level..

Answer 1

8th level, like feeblemind, would probably be best

Ignoring the pedigree here, and just looking at the pure effect. The text of this is not only modeled after, it is essentially identical to feeblemind, except for these two differences (plus, you probably should type the 4d6 damage as untyped damage is not really a normal thing in 5e; psychic still good there):

1. Range is 120 ft for Warp Mind, instead of 150 ft for Feeblemind
2. "On a failed save it suffers the effects of the confusion spell." instead of "On a failed save, the creature's Intelligence and Charisma scores become 1. The creature can't cast spells, activate magic items, understand language, or communicate in any intelligible way. The creature can, however, identify its friends, follow them, and even protect them."

I think it is not clear cut if perpetual confusion is weaker than feeblemind's effect. Feeblemind is clearly much stronger vs spellcasters. But look at brawlers like a fighter or barbarian, who still can "protect their friends", i.e. attack if feebleminded. This is the main thing they would do anyways, so in combat, feeblemind does relatively little against them, while confusion takes them out of action 80% of the time. While they have a 20% chance to act normally, they have a 60% chance to effectively do nothing, in particular, no attacks, and a 20% chance to attack their friends if those happen to stand next to them.

Likewise, the effect of confusion in social sitations is arguably worse. A feebleminded character can follow their friends around sheepishly and cause little harm or problems. A confused character however will attack somone at random on average every half minute, and is hard to control as they wander off randomly every minute on average too.

I don't really see how this is weaker -- spellcasters are typically more rare as opponents than brawlers, too. The main argument where this is clearly weaker is the shorter range, and range matters. Also spellcasters, even though rare may be especially dangerous. So I think 7th is not much off, but on balance, 8th like feeblemind seems to be a closer fit.