I hatched a myth banshee with myth dealer, myth giver, pain giver, and spell proof to a myth wartle with myth dealer, myth giver, spell proof, spell defying and fairy. I'm training this seemingly perfect pet and using most of my mega snacks and gold to do so. Then, when my pet reached ancient, it got the ability DEATH giver. HOW IS THIS EVEN POSSIBLE????!!!!! I'm really mad and I figured this has to be a glitch. Any advice?
Not a glitch. Pets carry "genes" for 10 talents and 10 derby abilities. Trained to mega, you can see 5 of each, but the ones that are not manifested are still there and can still pass when hatching.
The talents you see are more likely to come up more often, but not guarantied to. Like recessive genes in real creatures, sometimes there are unexpected traits. Your best bet is usually to stop training and rehatch any time you get something unwanted.