Some TMNT stuff was always meant for grownups.
As relayed in Dr. Letodd's Guide to Rare Crests, Aunkamen was a "rebel prince" who was so obsessed with becoming pharaoh, that he used black magic and psychology to enslave both living beings and inanimate objects. In the end, he never did attain his goal, but he lay a curse to come back when his tomb was opened.
In 1990, his tomb was reopened by Tech II, a development firm which had designs to build modern industrialization and a resort in Egypt. The Egyptian government had strict stipulations on protecting their undiscovered heritage. Thus, Tech II hired a team of archaeologists, which included Molly Rodriguez, to verify and document the discovery.
Molly rang for her friend April O'Neil to come and to assist her in documenting the discovery. Upon entering Aunkamen's Tomb, they were confronted by Aunkamen's guardian, Jackal, and were forced to become Aunkamen's brides.
Fortunately, April had faxed the Turtles before they went in, and they were well on their way to the rescue. They sloughed through the mummies and enchanted statues and broke Jackal's staff, Karnak, thus returning all to normal.
Or so they thought. Aunkamen's curse turned out to be independent of Jackal and Karnak, and he was still brought back to life. His tenure was short-lived, however, as he threw his own sarcophagus at the Turtles and hit a pillar, causing the tomb to collapse on him while Molly, April, and the Turtles escaped.