Game idea: you've got a series of spells you can use, which you cast by typing them.
But enemy bosses can attack your keyboard. Your "E" key is disabled. FIREBALL is out. ICE9? Also out. Guess they're getting hit with SUMMON FROG.
The bosses can also drop traps on your keys. So if N is trapped, you can cast SUMMON FROG, but the N-trap will go off and you'll take damage.
An advanced late game spell is THESAURUS, which lets you reanalyze a spell. Can't do SUMMON NIGHT WOLF because your N key is broken? THESAURUS it and now it's CREATE DARK DOG.
Another enemy attack would be putting a counter on your keys. So if they put a 1 on your R, you can cast "FIREBALL" but "CIRCLE OF TERROR" is right out.
The two can be combined: a trapped counter only goes off if you type more than the counter. So a trapped 2 on your S means "HEAL SELF" is fine but "TRANSFORM SELF TO SERPENT" will activate the trap and you'll take damage.
One late game boss attacks you by cutting your keyboard in half, and which half works alternates between turns. You gotta figure out which spells you can use that turn.
You could do some fun gimmick-fights. Like a boss sweeps your keyboard off the table and makes you play scrabble instead: you have to spell spells to cast them.
Or wheel of fortune, where you have to get enough money to be able to buy vowels before you can cast spells with vowels in them. The puzzle on the board is a spell the boss is going to cast against you, so it's also a fight against time. If you correctly guess too many letters, they'll solve and you'll get hit with the spell.
I think the way it works is that you fight some mooks and then a boss, and each boss has a new spell they can cast against you.
But you can cast any spell you've seen used against you, so like you start with merely FIREBALL but the first boss hits you with HIGH JUMP, and now you can use that ability out of battle, cause it's a metroidvania of course, and now new areas are accessible.
But bosses can use "forbidden" spells against you, and they do it by typing words you can't.
Like the viking boss hits you with a OΓNDLIG FJΓRIL and you don't have that letter.
(later you can upgrade your keyboard to get access to some forbidden letters, but at great cost: you must sacrifice a letter to gain it, and you don't get to pick which letter the keyboard surgeon will take)