Tarantulas always has cool stuff lying around; you're certain he'll have some kind of device that can give you the power to defeat Megatron. Not that you're going to ask Tarantulas if you can borrow it, of course.

You sneak down to the area Tarantulas has claimed as his lair. Fortunately, he's out, probably hunting mice again. And you're even more in luck - he happens to have two odd little pieces of equipment lying right out where you can grab them. One seems to be the Transmetalizer from the Insecticomic Fun With Transmetals ... but it didn't quite work then. You have no idea what the other thing is. Which one do you take?

The Transmetalizer. Maybe Tarantulas fixed it.
Take the other thing. Why not?