Aster's Mind Siphon

A strand of psychic energy lances toward a creature within range, forming a sustained mental connection between you and the target. Make a ranged spell attack against it. On a hit, the target takes 2d8 Psychic damage and subtract 1d4 from the next saving throw it makes before the end of your next turn.

On each of your subsequent turns, you can take a Bonus Action to deal 1d8 psychic damage and subtract 1d4 from the next saving throw it makes before the end of your next turn to the target automatically, even if the first attack missed.

The spell ends if the target is ever outside the spell’s range or if it has Total Cover from you.

Using a Higher-Level Spell Slot. The initial damage increases by 1d8 for each spell slot level above 1.