It's too strong, in a rather obvious way. Its Banisher of Radiance on a 2700 body that can protect itself from being targeted (and Banishes in retaliation, tough luck 101). And also burns for a very reasonable amount per turn. At the same time its summoning condition is very simple and doesn't require any field or hand dedication. Grave-reliant decks might have trouble bringing out the usual answer, Exciton, against this. It needs a nerf.
However, it also could use a rework in its summoning condition. This card banishes indiscriminately. It would be ideal in a deck that wants its stuff to be banished. However, because such a deck keeps their stuff banished, the summoning condition, that would otherwise be a piece of cake, becomes awkward. Specifically, running multiples of this could be problematic.
- Change the summoning condition to: "Banish 2 Spellcaster-Type monsters from your Graveyard OR return 2 of your Banished Spellcaster-Type monsters to your deck"
- Lower Level to 7, and ATK to 2500. This allows the opponent to ram some stuff in it. Level 8s have some good blanket support and synergy, while Level 7s do have some options specifically with Spellcasters, so I think this is more of a trade-off tweak than a direct nerf.
- While I'm at it, I'd suggest an indirect nerf in making it WIND instead of LIGHT. This would make it non-Honestable and keep it away from some generic usage that LIGHTs have. I also think it's a nice idea conceptually, with the memories scattering in the wind and all. Maybe that's just me though.
- Lastly I'd change its protection effect. I'd get rid of the part that Banishes the offending target, this will at least let the opponent try to kill your hand without losing disproportionately much in exchange. In return I'd get rid of the OPT clause and make it so that it can react to stuff that targets more than 1 card (namely "negate the effect of a card that targets 1 or more cards you control, including at least 1 Spellcaster-Type monster"). This is generally a buff rather than a nerf, overall, but I think with the stats reduction it's fine.
EDIT: Oh and some OCG - Banish from, and one extra ; in the negation effect that should be a comma.