
Such a weird card that obviously rocks in Finn Edwards.
When to play it? Check if your location has enough clues (better in multiplayer, of course) and a higher shroud value than the enemy's evade value. That's it, you're good to go! Usually with Finn you are a bit better at evading that at investigating, anyway, so Transmogrify lets you gather clues with a higher chance of success and without spending an action.
Combine this with Bait and Switch or Gené Beauregard to milk the attached enemy even further by either moving clues to its location OR bringing it with you as you move to the next location yourself.