Thanks, Michele. You need to hit the door with something you can find on a shelf in the east. There are two skull faces on walls. They look like twins. You have to hit the skulls in the right order. Save first before you hit them so you can redo. They remove a column.
To remove the guy who is blocking your way, you have to find a sphere. Tap the sphere to remove the troll guard. As Michele says, in the southeast there are many crackable walls. Hit them.
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