as an athletics attack action, you fire a stronger arcane arm that wraps around a creature within 45 feet. the creature must make a strength/ dex save with a  dc equal to 10+ your strength modifier, if they fail, the creature is grappled and takes 1d12 slashing damage, the arm lasts as long as concentration is maintained up to 4 rounds, every time it is the grappled creatures turn, they can try the save again, if they succeed at any point, the arm is destroyed. if extending grapple's effects are ended, the arm dispels