A note on windy druids if you've never played one. You're either the type of person who can stand the borked-ass nature of targeting with nado, or you aren't. Nado does have a bit of a technique to it, but even after I felt like I figured it out, I'd still have trouble hitting a single target at certain ranges. It's a bit inconsistent and can be pretty frustrating, at least for me.
If you go summon necro, get a staff with tele charges asap, as you'll need to force your minions to target specific enemies. As far as general mobbing goes, once one minion with a moderately high heal pool dies, exploding the entire room is pretty fun. It's also about as safe as you can get in pvm, so there's nothing stopping you from dumping nothing but mf gear on it and watching all the pretty colors appear. There's nothing really intuitive about the build though so it can be boring.