I have been playing around with fireball since noticing that it was shortchanging me a damage when choosing just one target. In my most recent game I cast fireball twice. The first time was for 16 total mana to spread 14 damage over two targets with the result being six damage to each target instead of seven. The second time I cast it for four mana with two targets. I targeted my opponent and a 5/6 Boartuk Liege with no damage on it. This should have done one damage to each, but it instead made the Boartusk leave. I say leave as it is not in play, in my graveyard, hand, exiled, or on top of my library. I just replicated this last example in another game and made note of my opponents deck size etc at the time. Four mana fireball divided between a 3/3 and my opponent. Opponent took no damage and the creature again disappeared from the game. Creature was enchanted with giant strength which went to graveyard. Opponents hand and deck size were same before and after fireball so it did not end up in either of those.