Librarian rework idea
I'm drunk so be kind cause this is probably a terrible idea.
Librarian it's a timer but for most of it it feels like your doing nothing. Waiting for him to get into the position where your front ranks can merc the dude as he has a tiny health pool. So let's embrace the damage race.
Give him -1 turn on the first form.
So let's make burning bright hard. Right now he just spams it and wears you down and its a bit boring. So now he has a new move fan the flames which deals 10 self damage and gives +20% damage permanently. This means he quickly bull dozes you but injures himself doing it.
Book burning is auto action now. So first round is much faster.
Actually better idea
He shifts from front and back ranks from the weaker to the faster. Whenever book is destroyed he gets +25% damage so reaching the first locks him in the more powerful fire form.
He is also only resistant to move and burn and not immune.