The Subterfuge skill is a class skill that the Deceiver class gains. It is used to make disguise kits which anyone regardless of class can use to disguise themselves as something else.
Skill Use
You can access the disguise kit crafting screen via the Inventory > Tradeskill > Subterfuge menu.
The subterfuge screen provides a list of all of the disguise plans you have enough skill to make kits for. You do not need to buy plans from a trainer you simply need enough skill for the plan to show up automatically.
Select the plan you wish to make a disguise kit for then click the Make button you will gain a purple skill gain and the kit will be added to your crafting queue.
You can retrieve your completed kits once they are finished via the Inventory > Queue screen at which point you will also receive any experience you earned from making the kits.
While only people with subterfuge skill can make these kits anyone can use one.
Using a Kit
Simply go to the Inventory > Containers screen select your chosen disguise kit and click the use button. The kit will be consumed but you will be disguised.
Reasons for disguising may include:
After using a disguise kit you can remove the effects by going to the Character > Info screen and clicking the Remove button.