Yes, I saw this immediately. I /bugged it in game. There is NO way this was intended. It makes the spell nearly unusable as it takes close to half my mana pool.
For the last level or two, I've been doing a fair amount of solo'ing on the same mob types. I could kill two to three of them in succession. Now, if natures wrath fires, I cannot even do two before going out of mana...One stretches me, but if working to be very efficient, I can do two.
I'm not one to complain about balance, as I've been having a good time with my druid. However, this increases down time significantly, while taking away the ability to take out some mobs I could, with work, before.
Did we really need to be taken down in strength? This has to be a bug. Is anyone able to recall what the mana cost was before, and when it changed?