Arachnid doesn't work

How do I get an arachnid to work? I throw him down and nothing happens.

 

You merely equip it into your quick item slot and use it like you would say a potion. click on the pic of it in the quickslot and then click where you want to throw it.

 

If this is a standard arachnid, Chunky is absolutely correct. You should be able to use it like a potion.

If this is a medical arachnid and you made it yourself from the schematic, unless you have the corrected schematic installed, it won't work. There are two medical arachnid prototypes for some reason and only one of them actually works. In the original schematic the non-functional prototype is referenced and the only functional medical arachnid is the one you get from Maxim. There is a fix for that available if you don't have it at http://www.rpgplanet.com/arcanum/tinker ... erer.shtml where you want to get Krupp's All in One Fix.