A wolf

You had decided to combine him with a wolf. You had the man strapped naked onto a table. He was a little difficult at first, but after you cast a dizzy spell on him he was much easier to handle. The ritual could begin.

You collected some wolf hairs and placed them on the man's stomach. You placed your hand over it and summoned your magic. This put an ethereal glow over your subject. The man started to become worried and asked "What are you doing?"

You chose to ignore him and continue the spell.

"Stop it." He said softly.

You continued to ignore him and persisted the spell.

The man began breathing heavily. He felt something was happening to him.

"Stop it! Stop it, please! Somebody, help me!" He tried to yell. He was too dizzy to resist at all and was completely at your mercy.

Finally the preparations were complete. The merging could begin.

The man's stomach became like liquid, allowing the hairs to disappear into it. While they were absorbed by the man's body, he started to change.

His ears moved up his head and became pointy. Next he grew a think, medium sized tail, and hair covered both his tail and ears.

At some moment he opened his mouth and you saw some of his teeth, sharpen just a little.

The last thing to change were his nails, which turned into claws.

Once that was done, the merging was complete. You ended the spell and retracted your hand.

You had turned the man into a wolf-boy.