Cut of Hadar

You Invoke the Power of Hadar, the dark hunger, and infuse your sword with it, then tou create a cut hovering in the air on a square within range. This cut serves as a Portal to Hadar and if you stop concentrating on the spell, dark tendrils erupt from within the cut in an area of 10ft in front of it and 5ft to either side. For each round you concentrate on the spell, to a maximum of 5 rounds,  the range increases by 5ft. Every creature in the space that the tendrils occupy takes 6d8 necrotic damage and is forced to make a strength saving throw being grappled on a failure. The grapple ends when you stop concentrating on the spell. Or until the creature succeeds on an Athletics check against your spell save DC.