Dark Hearted Hero: Champion of the Eternal Night

Two days after "Titans Together" Slade strikes the weakened Teen Titans with a grand plan to break the Titans once and for all which culminates in the death of Beastboy or does it? Before his life is lost, Beastboy finds himself saved by a dark and mysterious being with powers never seen. Why did it save Beastboy and what will be the consequences of this choice? AU