OOC:
Look like the game may benefit of DMs interruption, let me narrate that:
You spend some time investigating the book with no benefit, eventually you decide to try pulling the handle and it triggers one of the towers to cast
[ +- ] Lightning Lure
You create a lash of lightning energy that strikes at one creature of your choice that you can see within 15 feet of you. The target must succeed on a Strength saving throw or be pulled up to 10 feet in a straight line toward you and then take 1d8 lightning damage if it is within 5 feet of you.
automatically targeting tallest of you - i.t. Mal who is looking into the book (I believe bugbear has to be tallest of you)
Surprised about this Mal is pulled to the tower and takes 8 points of lightning damage
You also notice that white cubes in the room start melting. Group decide not not interfere with the the hazardous equipment move through the doors discovering a chest behind it. Chest as usually contains some food and - this time a scroll. The scroll appears to be "Protection from Evil and Good" spell.