Actually, as per this vampiric dnd 5e touch spell, a touch of your shadow-wreathed hand could be a siphon force from some others to heal your different wounds. So that, you can make a melee spell attack which is against to a creature within your range of reach. But on a particular hit, the target can take 3d6 necrotic damage, and even you would regain the hit points which are equal to half the amount of your necrotic damage dealt. Unless until the spell will be end, you can make an attack once more on each of your turns like an action.
Also read: mind spike 5e spell
At Higher Levels: As we discussed above, whenever you cast this vampiric 5e spell by using the spell slot of 4th level or more than it, then the damage will increase by 1d6 for each slot level above 3rd.
Attributes Of Vampiric Touch DnD 5E Spell
|Casting Time||1 action|
|Duration||Up to 1 minute|
|Higher Spell Slot Dice||1|
|Higher Spell Slot Die||d6|
|Target||A creature within your reach|