I haven't seen other people mention that bug. It seems to happen when I get killed specifically by a volcano ( yep, it's great for world 50...) ?
I will permanently lose one of the spells I have equipped. Like, it is marked as if I don't own it anymore and it gets unselected in my assigned mouse buttons spells, forever. I just lost the possession spell halfway through world 50 and everything else works just fine.
Any one seen that?

Volcano trauma... :/

I haven't seen or heard of losing spells like that mid-level. You could try claiming another copy by killing an enemy wizard and collecting it from their corpse, or check your corpse to see if it is there.

I tried that and a spell jar does appear but can't be picked up. When going on it it just makes some spell in the map screen turn to a black square. It's very strange, wonder how I got a unique bug like this.
I got to hidden world now, will see if it still happens there.

I'm glad you managed to beat it. Good luck in Hidden Worlds!

Thanks!
Ah another thing I get ( just happened in hidden world too) is the fusing bug that you get with meteors but with volcanoes on castles. Which is a bummer because they re really fun to use...

Ack... Actually, is there a way to avoid the fuse castle bug to happen with meteor? I thought I had read this was patched out of Hidden worlds but it's def still happening for me even with the new homing meteor spell, making some levels really frustrating. :c

I'm not sure of a way. I've found that lightning is better spell for razing castles, if you have the mana. Also, I seem to recall that if the enemy wizard is around, they are able to rebuild their castle almost instantly when it goes down a level, which makes things harder.

Yeah I mostly use the big lightning most of the time and undead army, but enjoyed the pyrotechnics while grabbing mana :P
I'm getting more and more crazy bugs and crashes now, wondering if saves can somehow get corrupted. I think I m just gonna play levels until I clearly have the upper hand and if it bugs I ll just use the cheat to go to the next :/

New insane bugs I got, just for fun:
- all monsters work normally but aren't animated anymore
- got a fused castle while using lightning AND the wizard stayed permanently super agro with glitched balloons floating around. That wizard would revive instantly (not even a second delay) after death and respawn directly in my castle.
- all text on screen has multiple long horizontal lines across them making them mostly unreadable
x)

( still is one of my favorite game though haha )

I don't even know what to say to any of that. XD

My playthrough was mostly bug free. Wizards would revive almost instantly after death later on, but killing them and grabbing their corpse was an easy way to claim the loose mana that popped out when I deleveled their castle for them.