When spores of Hydrus Aurum enter the digestive tract they nest inside the stomach where acid keeps it from advancing too fast. Over a couple of days, by eating food consumed by its host, it grows large enough to fill the stomach entirely.

Effect

• Stage 1 Once the infected creature has eaten 2 days worth of food , it will feel light abdominal pain. The creature suffers 1 level of Exhaustion and can’t be reduced to below 1 level of Exhaustion until it’s cured.
• Stage 2 Once the infected creature has eaten 4 days worth of food, it will start feeling weak, as if it hasn't eaten in a day. The creature suffers 2 levels of Exhaustion and can’t be reduced to below 2 levels of Exhaustion until it’s cured.
• Stage 3 Once the infected creature has eaten 8 days worth of food, it will have its stomach filled by Hydrus Aurum, making it hard to breathe. The creature suffers 3 levels of Exhaustion and can’t be reduced to below 3 levels of Exhaustion until it’s cured. At this stage, the creature can’t eat, as it instantly regurgitates any food it attempts to eat due to stomach blockage.

Transmission & Contraction
A creature that drinks water contaminated by spores of Hydrus Aurum contracts Golden Gut if it has eaten that day. Hydrus Aurum spores can survive up to 30 days in water before dying, but the spores instantly die if the water it’s in is targeted by a spell or effect that deals Lightning damage.

Curses & Treatments
Dealing 10 or more Lightning damage to the infected creature will cure it by bursting the Hydrus Aurum inside it. At Stage 1 the burst will deal 4d10 Bludgeoning damage to the infected creature. This damage increases to 8d10 at Stage 2 and 12d10 at Stage 3. The creature must then make a DC 15 Constitution Save. Failure: It falls Unconscious. Alternatively, when at Stage 1 or 2, a skilled doctor with adequate tools may try to extract it with an invasive procedure through its mouth. To do so, the creature attempting the procedure must make a DC 20 Medicine Check during a Long Rest.

Success: The infected creature is cured.

Failure: The infected creature is reduced to 0 HP and begins making Death Saves at DisADV and can’t be stabilized or regain HP until it takes 1 or more Lightning damage.