New Invis Hero

Invis Hero
Melee
Passive: Bonus ms while Invis
1st Spell: Assassinate Stronger attack, While Invis: More Dmg, Hits from behind, Even more Dmg Plus Stun
2nd Spell: Invis Goes Invis for a duration
3rd Spell: Passive Lifesteal Activate for Bonus Dmg and As
Ult: Something like Noc's ult

Hmm, Interesting Concept...

1st spell - This spell is a great idea, perhaps i can integrate this as a passive for allowing a hero to deal more damage when hitting from behind, as well as giving it a chance to teleport behind an enemy when attacked or when attacking.

2nd spell - Alright, this sounds like a short duration windwalk.

3rd spell - Interesting... This spell could serve many purposes, activation when assassinating a hero from invis or just straight out fighting, although i think it can use some small tweaks it sounds good overall.

Ultimate - I think you should elaborate more on this ability, the current description is a bit vague. I recognize your reference to Nocturne from League of Legends, but the concept is still very vague, im afraid i cannot get many ideas out of this.

Overall - The hero may not be implemented, although some parts might be used in several other heroes.