Drink the demon potion.

Looking over what you have, you decide the only one that has a good chance of getting you out of here, and getting whatever is growing in you, out of you, is the potion that turns you into a demon, gambling that whatever is inside you can't survive being inside of a demon. “Bottoms up.” You say cheerfully and down the sickly sweet liquid. A second passes and you are sure it isn't doing anything, before your body seems to burst into flames. The heat is intense but welcome, and while unnerving, it doesn't hurt so much as feel like you are sitting in front of a furnace vent in the winter. In a matter of but a few moments your arms split and multiply till you have 3 on each side, your legs fuse together to form a long tail of a snake, and you become totally female. As the change completes you are now aware that you now have the ability to instantly create from nothing any weapon you can think of, you are immune to most attacks, and you can unleash a variety of spells on any enemy you face, some are instantly apparent, such as summoning a ball of flame, summoning creepy monsters, or influencing the minds of others, others are rather odd but if all else fails you can attempt one to see what happens. However you also know that each time you use magic it lessens the duration of the change. As it stands now if you use no other magic the potion will wear off in a day.

Taking a moment to look around you summon a cluster of 6 wicked serrated edge long swords. Slithering up to the wall of the room you are taken aback as suddenly there is a warm feeling inside of you, a few seconds later you see your distended belly flatten as the mass inside of you is simply digested. A big belch escapes your lips as you carve into the wall of the creature. Several hacks later and you are covered with black and reddish slime and gore, the walls and surrounding area spasms and writhes trying to crush you, then as you burst out of the creature you are assaulted by the tentacles. One slams into you mouth much like before, yet this time as it does it recoils as if burned and you bite off the tip with your powerful mouth. A few gore soaked moments later and you have hacked every last moving piece into a wiggling squirming hunk of unattached monster bits.

Looking around with a smile you check your satchel to be sure it is safely on your back, and head out into the sewer. Several times you see movement, but nothing, intelligent or not, seems to be even slightly interested in tangling with something that radiates such a sense of evil as you do now. It takes a good couple of hours to find a way out of the labyrinth like depths of the sewer, but eventually you do find a grate that once you rip it down you find yourself at the edge of a small stream. Strolling out of the sewer you look around and see a massive ancient walled city surrounded by what seems to be a rather desert like landscape. The small stream you are next to flows down the southern edge of the city and empties just at the edge of your sight into a massive body of water that is either a lake or ocean. You are pretty sure that walking back into the city like this will get you attacked by guards or something, but you also have no idea where else to go.