Invisibility Potion

Invisibility Potion was introduced in the 1.0.5 patch. It turns the player invisible for 1 minute, though equipped armor seems to remain visible. All AI types are still able to target you. You could, however, take off all armor to render yourself invisible in PVP at the cost of a lack of defense.

Note
Whilst wearing the Familiar Clothes you will be rendered invisible regardless of the armor underneath; however in PVP since it disregards vanity items your armor will still be visible.