Okay for now I'm going to leave the debate over the EP price alone for now, firstly I don't go for the whole so many use things. Instead I enjoy cooldowns for such things but just to let you know that doing the cooldown trick makes one have to pay more for the form than say those forms that give abilities that still cost EP -like Mystic's one form-
So first skyward dash......that is just used to move really fast toward something or somewhere right.......okay then first need a distance for it as well as a cooldown for it......the further the distance covered the longer the cooldown between uses I will ask for. Hmm I say that for every three yards covered equals 1 post of cooldown, so if you want to cover 9 yards of distance it will come with a 3 post cooldown phase. This is of course assuming the attack doesn't do any harm of its own directly.
Fury Slash is a heavy one target Shadow attack if I am right......so that will be a 4 post cooldown at least........also you got me confused on it. Zero can preform a slow yet devastating attack at one point you say that so the attack is slow.......but then you type out downward with great power and speed for which implies it is a fast attack........Make up your mind is it slow or fast?
Lastly Teleport.....that......that is one that makes me twitchy.......Teleport is more of a Space ability since to teleport you bend space around you to allow yourself to move from one location to another without any active movement taking place. So I rather you use another way to make a "I dodge this" attack if you must, but once you do the cooldown for such a move is going to be long since normally negating an attack requires paying the same amount of EP as the attacker used. I do it like that to keep it fair......so you got a choice make that move alone have a EP cost that varies based on what ever is thrown at you OR take a 7 post cooldown for it.
Lastly in your disadvantages how long does that 10% speed drop last once you change back?