Homebrew, Ravenloft: Denizens of Darkness (3.5e)
Dread Heart Seeds. A creature that has a dread heart seed implanted in its body requires a DC 10 Wisdom (Medicine) check to remove the seed within the first 24 hours.
After 24 hours, the creature takes 2 (1d4) necrotic damage at the dawn of each day as the seed's roots begin to sprout in the creature's body. The creature's maximum hit points are reduced equal to the necrotic damage, & can not be restored until the seed is removed. If the creature is reduced to 0 hit points while implanted with the seed, it dies and a dread heart tree sapling will sprout from its corpse in 4 (1d6 + 1) months.
To remove a seed after 24 hours requires a successful DC 15 Wisdom (Medicine) check that can only be performed once per day. A casting of the Remove Curse spell will also expell the seed from the creature's body.
Magic Resistance. The dread heart tree has advantage on saving throws against spells and other magical effects.
Tendril. Melee Weapon Attack: +3 to hit, 5' reach, one creature. Hit: 4 (1d6 + 1) piercing damage. The creature must succeed on a DC 15 Constitution saving throw or have a dread heart seed implanted in the creature's body.
Seed Shot. Ranged Weapon Attack: +3 to hit, range 30'/60', one creature. Hit: 3 (1d4 + 1) piercing damage. The creature must succeed on a DC 15 Constitution saving throw or have a dread heart seed implanted in the creature's body.
Tropical Climates; Grassland, Forest, Hill, Swamp