Just to clarify, do you want a Master of Many Forms or do you want a dude that summons eldritch augmentations to smite his foes?

You keep saying things like "turn into a shark" or "turn into a scorpion" if thats really what you want to do then i think you're going the wrong rout entirely. Your presented fluff is more of a "you alter your body" type of shape shifting. So a better description of your scorpion would be:

The mans arms and legs become long and stick like, other pairs of legs erupt from his ribcage and his hands turn into strong looking pincers. Finally the mans tailbone extends into a long arching tail with a wicked looking stinger dripping poison. He smiles at you with his still human eyes as his mouth fills with sharp teeth.

He only becomes a mechanical scorpion, he only superficially looks like one. I personally like the idea of the eldritch abomination, but if thats not wht ur going for thats cool too, we just need to know in order to give any meaningfull input.

Also trying to balance a class to T1 casters is... Ill advised