The blessed pot is a quest item created by taking a silver pot made by Ruantun to be blessed by the High Priest on Entrana.
Talking to Malak will let him damage you for 5 hitpoints, filling the pot with blood. Spices and garlic must then be added (in either order) to complete it, after which it can be used to summon Dessous. If the player has 5 or less hitpoints, he will do damage that leaves at least 1 hitpoint. It should also be noted that even if the player has one hitpoint, he will instead hit a zero and the player will still obtain a pot with their blood.
After the player completes their task from Malak and collects the blood diamond, he will confiscate the pot (all variants) from the player's inventory or bank. Should the player wish to keep it or a copy, they should drop it before speaking to Malak. If the player loses the blood diamond and reclaims it from him, he will again confiscate any blessed pots the player may have in their possession.