Hi guys!
When 5.0 came out you where able to climb walls by just placing a Mushroom and Wild Charging there. That one got fixed as it often says "No path available" when you are trying to place the mushroom.
You are still able to send your Treants (Force of Nature) to many locations though. By charging them you can climb mountains very easily.
Here I'm using this method to reach the top of the Deadmines gate: