In development, the team tried out a vanishing mechanic where a summon-like creature would slowly die over several turns, which was read as a downside
In Commander, mana dorks are run in the majority of green decks, so this seems like an easy ramp staple
This fuels a brutally efficient go-wide aggro strategy, flooding the board with cheap vampires that quickly become an overwhelming army
That means Not Dead After All, Spellbook Vendor, and Lord Skitter's Blessing are actually Auras in disguise
Additionally, Emry possesses the immensely useful capability of reducing her own mana cost by one mana for each artifact you control
Lets say it was a 1/2 for 1W with a clue you could sac for 1 it would be substantially worse