Nehs, the Shadow Tank

I saw a post about how Shen makes an awful Ninja. I thought about what it would take to be considered a ninja tank. I saw another post suggesting a temporary damage mechanic and thought: A ninja tank could use an ability like that. What else would a ninja tank need in his kit?

Passive: Crit is converted to tenacity. Meaning he can never have crit. Q: Skill shot AoE Blind (Scales with AD) W: Spell Shield E: Dash R: Targeted attack applies an execute amount of damage that is slowly healed back. (Scales with AD)

This was just a quick concept I felt like putting together. I think with some thought put into it, it could be a great concept.