Usually, on level 10, if I don’t have a magic spell holder, I just drop all my spells before opening the door to Tengu. At the end of the battle, my spells are there (along with Tengu’s mask) for me to pick up.
This time, I forgot to drop the spells before the first phase of the fight. Fearing getting caught in one of Tengu’s firewalls and losing some spells, I dropped them on the hallway before opening the door to the second phase. However, only the upgrade scrolls were there after the fight! I lost several spells, including a couple of remove curse and identify.
Is this intended, or is it a bug?
FWIW I usually drop them in the room where his first phase takes place. So at least there they are recovered.
I usually drop them in the small room with the stairs, which also works.