I've been in a journey of building a MvC2 collection, most of the characters have figures or are simple enough customs, blackheart is definitely the latter.
Base body is the Masterverse scareglow Wich is the basic Masterverse male build, main reason I choose him was because his joints are already black so it helps with paint chipping.
It's a pretty straight forward custom, it's a black naked guy with a tail, the most drastic modification I did to him was extending his thighs to better mach the in-game sprite, did that by using hot water to separate the hips from the thighs, put a tiny amount of Vaseline around the thigh swivel peg and covered it with hot glue, I then attached the thighs to it, creating longer legs.
Once I did the mod, I sculpted over the thighs and pelvis (had to cover where the skirt sit) I then attached skeletor's lower legs for the feet, sanded all the boot detail and sculpted over it, head, hands and tail we're all made from scratch using air dry clay, covered him with matte black and air brushed some blue.
Pretty happy with how he turned out, maybe I'll go after the toybiz Blackheart head in the future, but for now, this is how he's going on the shelf