Vampiric Bite

You can drain blood and life energy from a willing creature, or one that is grappled by you, incapacitated, or restrained to heal your wounds and satiate your thirst. Make a melee spell attack against a creature within your reach. On a hit, the target takes 1d6 necrotic damage, and you regain hit points equal to the amount of necrotic damage dealt. The target's hit point maximum is reduced for 1 hour by an amount equal to the necrotic damage it took. Any effect that removes a disease allows a creature's hit point maximum to return to normal before that time passes.

At Higher Levels. Your thirst consumes you, requiring you to drain even more spirit to feed your unending hunger.  You may cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st, up to 5d6. This enhancement feature may only be used once a day. Attempting to cast this spell again after heightening it, but before taking a long rest, requires a roll on the short-term madness table below before each additional cast.

Short-Term Madness

     D6                                                                                         Effect (lasts 1d10 minutes)