When we were testing Druid vs. Necro I playtested with Bridge Trolls. Yes, they were fantastic with a Druid, because they needed the same cards that the rest of her creatures do. So in that way your book is already build to use them. However, sharing the Flame weakness is pretty bad. In the end, you have a flame weakness and you're not a vine. All you gain for that is that you're not rooted, which has some benefits as well as downsides. Also, War costs triple for Druid, so I just avoid the Troll, for now.