Hi and welcome in our forum.
To use the Death Scorpions, you need the Deadly Gift skill (Way of the Survivor - Path of the Thief).
More detailed info regarding this skill can be found at
IGN There are three kind types of traps available in <img src="/ubbthreads/images/graemlins/div.gif" alt="" /> : Spider Mines, Trail Bombs and the Death Scorpions.
To be able to use any of these traps, you need to find (or buy) the corresponding objects in the game. Once you have these objects, selecting the deadly skill will pop up a submenu of available traps. Click on the icon in that submenu to select the trap you want to use. Right-click in the world to use your trap.
Hope this helps you.
*Moving thread to Help/Tips/Tricks Divinity*
