How do I use these books in Dungeons 2?

I keep discovering these books in my dungeon:

Hand of Doom holding a book

They seem to be upgrades, but I can't tell how to use them or if they're already enabled.

I think I remember the tutorial saying I need to equip them, but it didn't really explain how to do that.

So, are these upgrades? How do I use them? Are they already doing something?


Solution 1:

You have to pick them up, then drop them on whatever creature you would like to have that upgrade.