At minimum you'll be paying 3 mana to save your commander, draw and discard a card which feels like a fair deal for its mana cost and I can see many Dimir graveyard, discard, reanimator or Izzet/Grixis wheel deck slot this card for its instant speed potential
A spell with flash can be cast at instant speed, but flash is applied to sorcery-speed permanents like creatures and enchantments
Its a very efficient 2-drop creature with shadow, and you can cast a card for free if it was exiled with this card
Either way, I don't like it
Other than Worldspine Wurm all the best green targets fall in the pretty playable 7 CMC area
His abilities trigger even when hes in the Command Zone, building you a colossal army of Vampires to power up