Drav'yn, The Shattered Mind

Maybe OP caster and anticarry
http://dotaconcept.com/hero/1845

Curse of Insanity:
I feel like the first skill doesn't have much synergy with the rest of the hero's kit, being the only one dealing with magical damage. Perhaps lower the damage (50/100/150/200?), changing it to pure damage, and changing the magic resistance reduction to general damage amplification (15/20/25/30%?), like Chen's Penitence. Perhaps increase the mana cost to compensate perhaps for the high damage and amplification of the skill.

Mental Overload:
I don't have much to say about this skill. It is a good AoE nuke that scales well and is balanced.

Psychic Backlash:
Due to him being relatively squishy, this skill won't be able to proc too much, but it is a very powerful skill, made more powerful if he builds a Shiva's Guard or Lotus Orb to make him more durable. The only thing I would suggest is to make the scaling for the duration even (1/2/3/4) and maybe even a bit longer.

Sanity Break:
This is an interesting skill. I could see some pretty sneaky Roshan and Aegis steals with this. Makes team fights a lot more chaotic. There is a certain similarity between this and Winter Wyvern's ultimate, with this skill arguably being the stronger of the two. I would increase the cooldown of the skill (300/240/180? and 120? for Aghanim's Scepter upgrade.) Besides that, keeping everything else the same would make this skill more balanced I think.