A girl!
Ty wondered just why the pregnancy had advanced so fast in just a day. His best guess was that in order to give Heather all those orgasms he had to speed up some parts of her metabolism and he just sped up too much.
He used his magic powers to clean up the mess caused by the birth and return Heather to good physical condition and said "It's a girl, Heather! Now we need to name her..."
"Yeah," said Heather, "we need to name her. How about... oh, Denise... wait, that sort of sounds like Dusty... wait, Dusty, that name is familiar when I say it... I... oh, Ty, I was Dustin and you changed me!"
"What are you talking about, Heather?" said Ty. Of course he knew just what Heather was talking about. In order to make Dustin think he was Heather, Ty didn't use his own power, which didn't work that way. Instead he got his friend Buster to help by hypnotizing him. It seems that Buster's power must be wearing off.