The shade ability is awesome, and the use of Grixis colors fits him well! A note on semantics: Since Core Set 2011, the Fear keyword has been changed to Intimidate. The only difference is that it's no longer restricted to black, and specifies "creatures of the same color"...not "black creatures".
I feel like Deathtouch is a bit strange flavor-wise on Sombra, he touched Shining Armor, and Shining Armor didn't die... I like the idea of being unblockable by less than a few creatures (as a massive cloud of shadow, he's hard to keep at bay alone). Interesting reference to shades, and you've worked in his enslavement shtick, which is pretty cool.