RPGMemes

Druids keep their hit points, so it would be a very hard to kill small creature, and it has to be a pretty high level druid able to wildshape into a hummingbird. I don't think such small animals are available in the current version, a 12th level druid in version 3.5 can wildshape into a tiny animal, but I think a hummingbird would be a size category smaller than a rat, which isn't available until epic levels (beyond level 20)

Also a 12th level wildshaped druid is more than a match to anything in a castle. They have access to their magic after level 6. Igor would be in trouble