Black Experiment Dragon

Multi-atttack: you can make one cursed Bite and one gripping Vine attack.

Cursed Bite: natural weapon attack: +3 to hit, reach 5 ft., # target. Hit: 5 (1d6 + 3) [necrotic] damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw against the curse or become cursed until the curse is removed. Every hour that elapses, the target must repeat the saving throw, reducing its hit point maximum by 3 (1d6) on a failure. The curse no longer reduces hit point maximum on a success. The target dies if the curse reduces its hit point maximum to 0. This reduction to the target's hit point maximum lasts until the curse is removed. The curse may be removed at a temple for 500 gp, with remove Curse, or with similar magic.

Gripping Vine. Weapon Attack: +3 to hit, range 20/40 ft., 1 target. Hit: 8 (2d4 + 3) [bludgeoning] damage.

Mind-binding Breath: Breath weapon, recharges on a 6 on a d6 roll: The dragon breathes a cone of sickly sweet air in a 30 foot cone. Every creature in the cone must make a DC 12 intelligence saving throw. On a failure:

The breath crafts an illusion that takes root in the mind of the target. The phantasm includes sound, temperature, and other stimuli, also evident only to the creature. The target believes it is in melee with the dragon, and will take 3 (1d6) [psychic] damage each turn as the mind fully so believes the illusion that it takes damage. 

The target can use its action to examine the phantasm with an Intelligence (Investigation) check against your spell save DC. If the check succeeds, the target realizes that the phantasm is an illusion, and the effect ends.

Roots unto the depths: you can move a creature this dragon hit with its gripping Vine attack, calculate the distance of how far this creature was from its target when it launched the attack. Then push the creature in a straight line in any direction the difference between the distance of yourself and them when you attacked, from the total extended range attack. 

Extra Bite. When this creature is is attacked:  it can cause any creature it has cursed that is Within range one of the dragon's senses to make a weapon attack on a target of the dragon's choice.