You create a tentacle made a blood to attack a creature you can see within range. Make a melee spell attack against the creature. On a hit, it takes 1d4 bludgeoning damage, and it must succeed on a constitution saving throw or take 1d4 necrotic damage and be poisoned until the start of your next turn. This damage increases to 2d4 and 2d4 at 5th level, 3d4 and 3d4 at 11th level, and 4d4 and 4d4 at 17th level.