Spell Feedback!

Hello all! I've been making Homebrew stuff for a while now, and I don't usually post it. This is the second spell that I've made, and I want some feedback on what I could do to improve it/If people like it or not.

Arklium's "In Absentia"

I'm not entirely clear on what the effect of the spell is actually supposed to be. Is the idea that when you're attacked, you can use your reaction to make the attacker forget you exist? If that's the case, I think the description needs to be a bit more clear on what that actually means in a mechanical sense, and how long the effect lasts for.

9th level seems a bit high for something like that. You only ever get one 9th level slot per day, and this spell is competing for that with stuff like Wish for Wizards and Mass Heal or True Resurrection for Clerics.

I might've worded it wrong. The intent is to erase the identity of the target creature, including from things like written records and other creature's memories. Or basically make the target completely braindead.