tendrils of darkness

when casting this spell 4 tendrils of darkness sprout from your back you can use them to do the following as a bonus action 

stab: you use one of you tendrils to stab a enemy within 30 feet of you roll for attack if it hits they take 1d6  piercing  damage and 1d6 necrotic  damage

grab:you use two of your tendrils to grab a enemy within 30 feet of you they mst roll a strength  saving throw  the DC is equivalent to your spell save DC is they fail the save  they become grappled  

swipe: you use one of your tendrils to swipe at a enemy within 15 feet they must make a dexterity  saving throw the DC is equivalent to your spell save DC if they fail they are sent back 15 feet 

charge:you use all four of you tendrils to charge for one turn of you do this you speed of doubled  for that round 

necrotic beam: you use one of your tendrils of darkness to shot a beam of necrotic energy at a enemy within 60 feet roll for the attack if it hits they take 1d4 necrotic  damage