so i'm on the final fight now, i've taken out all the other enemies that appear and now i have a problem. i can survive just fine but any time the divine and zandalor are at half health they just heal themselves repeatedly, theres nothing i can do to stop this and i cant just do enough damage to negate the healing, i made a video

http://www.youtube.com/watch?v=VQAjtDG_7Y4

now is this a bug or am i just doing something wrong