Ferret Bomber is a very scary card. It makes you discard 2 out of 10 (20%!) of your starting cards and is Sneaky. I'll Mindbug it often, but I may not Mindbug Ferret Bomber if I:
-Have a Compost Dragon or Giraffodile in my hand, so I can get back some discarded cards
-Have 2 cards in my hand that I don't need (e.g., if I have a Mysterious Mermaid in my hand but I have more health than the opponent)
-Have some easy way to defeat the Ferret Bomber (e.g., a Kangasauras Rex in hand, a creature with Hunter in my play area, a creature with Sneaky in my play area, etc.)
This is often great to play at the end of the game, when the opponent has no Mindbugs and only a few cards left. This forces them to make a really tough decision, as folks usually hold on to some great cards until the end. And of course, if you play it when the opponent has only 2 cards left...you can likely ensure a soul-crushing defeat haha