Blood Construct

You transform our own body with experimental blood magic and create constructs made of your flesh and blood.

For the duration, you gain one of the following benefits:

Tail Blades. Four tails composed of your blood sprout from your lower back, the tips of which harden into blades. As a bonus action for the duration, you can target up to two creatures you can see within 60 ft. of you - the targets must make a Dexterity saving throw, taking 10d8 slashing damage on a failure, or half as much on a success. 

Blood Wings. A pair of dark, crimson wings sprout from your back. You gain a flying speed of 60 ft. and you have advantage on Dexterity saving throws for the duration. Moreover, these wings try and follow-up when you deal damage - once per turn, when you deal damage to a creature within 60 ft. while concentrating on this spell, the target must make a Dexterity saving throw, taking 5d8 piercing damage on a failure, or half as much on a success.