I've never been very good with them, though. Honestly, Circle is very different from most other factions. So I want to simply post up some of the things I've learned over the last year. With the recent release of Morvahna the Dawnshadow, there are a lot of people coming into the druidic fold, maybe this can help!
Stones
Ok, these are super high on the list of priorities. Lots of people struggle with their use, but your enemies will know to kill these little suckers right away. First make sure you practice your deployment with them. There are tons of ways to setup your stones and the initial setup can make a huge difference.
This link is a great read on common stone formations. Play a few three turn games. Three turns is about as long as you should expect to be able to double teleport. After that, we've got assume that your opponent has killed one or both of your triangles.
Circle MUST abuse movement. If you don't, you'll find yourself losing a lot of games. Circle heavies and infantry is quite fragile. We can't stand toe to toe with many other factions, we've got to go in, hit hard and back out.
With a large triangle formation, I once charged Ghetorix into enemy infantry and cleared a few out. I was close to another rank of the enemy so I didn't want to stay there. I sprinted back 6" (Lightning Strikes), Warpath another 3" (Kromac) which placed him within the triangle formation. I then used the stones to teleport him another 6" back, placing Ghetorix 15" from the enemy line.
Ok, that's it for now. I'll move onto beasts next time. In the meantime, watch a champ play our faction: