The orc skin potion is a defensive potion. It is crafted by Lysis if she has access to two orc scalps. The orc skin potion gives the drinker the skin and base defense of an orc, increasing defense by 9 for about 1 minute. It also gives 20% acid resistance.
If you drink an orc skin potion while under the effect of the Stone Skin Potion or the Bone Skin Potion, it will override the potions effect (decreasing the defense by 10 or 8 respectively) and the message 'Your skin itches, then feels more sensitive.' will display.