Three plants

Lotus Vine

A long, creeping vine with broad leaves that produce a sweet, enticing aroma. It usually grows in areas with poor soil, especially sites of great suffering or cursed ground.

Through a process not fully understood, it transmutes curses in the vicinity into cursed fruit. The fruit are large, succulent pink orbs about the size of a fist full of seeds. Anyone eating one immediately believes it to be the most delicious thing they’ve ever eaten, and must pass a wisdom save. If they fail, they will refuse to eat or drink anything else except the lotus fruit. Once they’ve eaten all the fruit they can find nearby, the victim will begin frantically searching for more. This guarantees that when they inevitably die of hunger or thirst, their corpse will be a good distance from the original plant and the seedlings that burst out of them will have plenty of nutrients to get established.

A remove curse spell will free the victim from the compulsion to only eat lotus fruit, although nothing will ever taste quite as good to them again. It’s possible to keep a cursed victim alive by forcing them to eat and drink, but they’ll fight you as hard as they can and it’s not going to be fun for anyone.

The vine can be quite useful for slowly making cursed areas safe again, so long as you ensure nothing tries to eat the fruit.

Briar

The briar is a parasitic plant that looks like a bramble, but is absolutely covered in tiny, wickedly sharp thorns. Brushing up against it even lightly can break the skin, and when this happens there’s a 1 in 6 chance that the wound becomes infected. Falling into a patch of the briar guarantees infection.

An infected wound looks like a normal scratch or cut at first. It’ll become a little itchy perhaps, but nothing unusual for a normal cut. After a day or so, however, tiny tendrils begin to emerge from the wound.

At this point, it’s still possible to kill the infection by burning it out. This will hurt, of course, but since a briar infection is always fatal, this is a small price to pay. The problem is that the seedling produces powerful chemicals that make the host protective of it, and paranoid of everyone around them. On a failed wisdom save, the victim will conceal the infection to stop others from treating it. As the infection spreads through the body, they’ll become more irritable and withdrawn, desperately trying to conceal other tendrils that begin to emerge from the skin. After another day or if discovered, they’ll flail wildly at their former friends in hopes of infecting them with the thorny growths on their skin and then flee to die somewhere dark and quiet.

Characters get another saving throw every time something happens that might help them break the plant’s hold on their mind. For example, if another character risks their life to rescue them, the infected character’s conscience may help them break through and confess.

For extra fun, make everyone roll a wisdom save in secret every time anyone asks “was anyone infected in that fight?”

Inspiration Dust

Technically Inspiration Dust is the name for the spores of a rare mushroom. The mushroom itself is remarkably nondescript given its effects. The mushroom and its spores have the effect of creating a wild madness that can push the mind beyond its normal limits into genius.

If inhaled, the spores give that character +4 and disadvantage on all intelligence and wisdom rolls for 1d6 hours. If the mushroom is eaten, the effect is permanent instead. In this state, the GM can ask for a save whenever the character is trying to do something clever, or has a chance to do something that common sense would normally prevent them from doing.