After defeating the clockwork cabinet in battle you can chose to keep it as a follower. Can it later on be turned back into a trophie or does it stay a follower?

I just recently got The Frostmarch expansion which added the spell Toadify. When I played it the person I was playing with said that they were suppose to roll the die to see if the spell works, not me. The spells we are use to are like the Random spell which does say the other player rolls the die. If I play the Toadify spell, do I roll the die or does the player I cast the spell on?