Form 1: A good support hero. Alright.
Skill 1: I like it. No comment here really.
Skill 2: This is good too. It might be a bit OP in lane control but otherwise, it's good.
Skill 3: Too reminiscent of Dazzle's Shadow Wave IMO. My recommendation is to take Ladder Tranquility (partially because I'm desperate to see it in DotA? :P) and use that. Or, if you really wanna keep the chain aspect, "summons an owl to bestow a regenerative blessing. The owl will fly in a direction and all nearby allies will gain X HP regeneration for 5 seconds. If the blessed units come in contact with allies, the allies gain half of the regeneration for the remainder of the duration as well" or something like that.
Form 2: Okay, I'm not sure I really like this very much. This is an int hero with 2 support style forms and a DPS form now? On top of that, whereas the 1st form had no bonuses, this 1 comes with some powerful damage and HP bonuses. Not sure I like that.
Skill 1: Okay, I like this but, again, the DPS concept... Meh
Skill 2: Kind of counter synergetic with the melee range and doesn't fit too well with the DPS concept. Thematically, good, but otherwise... I dunno. An active really shouldn't countersynergise as much and 400 knockback makes you spend more time chasing than hitting.
Skill 3: A basic upgrade, still, a good one. I just worry since it takes so long... Oh well, otherwise, good. You might wanna reduce the number of stacks and increase the bonuses but that's just IMO.
Improvements: I think that here is a good opportunity for a previously suggested idea of mine. Your current version has a DPS concept which is meh but I understand why you might want it. However, Smash is counter synergising and frankly, sorry, feels like an attempt to just put an active in there so it's not a 3x passive hero. Also, anyone specializing in this particular form will feel obligated to increase their AGI some or stack up attack speed. So, my idea is simple: Replace smash with a skill which will improve attack speed and attack damage based on int. Like (.3/.4/.5% IAS and .3/.4/.5 bonus damage)
Form 3: I see this as a tank/scout... Which isn't really good for this hero haha... I suggest scout/disruptor. Take away the bonus resistance/armor and improve your MS boost and give flying vision.
Skill 1: It's good but reduce the cooldown to like 8 seconds. It's worse than a stun and deals no damage. Also, make it scale... Everyone else scales but the crow just loses out
Something like 1.15/1.3/1.45/1.7 duration with 12/11/10/9 cooldown would be good.
Skill 2: Again, unfitting, especially considering the fact that you can't even attack in this form. Also, while this form is great for chasing, well... This skill doesn't cut it for damage, especially with a 10 second cooldown.
Skill 3: I like this skill. Damage should be magical though. No point in trying to fit it in with skill 2 when skill 2 doesn't really fit in much anyway...
Improvements: I think skill 2 could be remade into a spammable single target spell that deals damage based on INT. This makes up for the fact that he can't attack and will allow him to use the chasing potential to it's full potential. I think it would do well with like a .25 second stun and up to 1.6x int damage with a 3 second cooldown. That'd be good IMO. It would, instead of some pseudo support disruptor, make him a full blown disruptor with some great chasing skill.
Well, that's my take on it. I might be asking for too many changes xD but there's some unfitting stuff in your skill sets... Overall, it's a good go but shapeshifting heroes are difficult and there are lots of changes to be done to compensate.