Metamorphosis (Gargoyles)

"Metamorphosis" is the fifteenth episode of Gargoyles, and the tenth single-part episode of the series.

Plot
Geneticist Doctor Sevarius was hired by Xanatos to create replicas of the Gargoyles, but the mutations he's created are a cross between jungle cats, bats and electric eels. Derek shields Xanatos from an attack and is infected by the Mutate serum, but the Gargoyles raid the facility before Sevarius is complete and he is killed indirectly as a result.