Its power level is more than acceptable for the set, however, meaning there's no reason for it not to appear in the Bloomburrow set
(You gain card advantage each time a spell you control resolves and you end up having more cards relative to your opponents than before that spell resolved
Yes, changelings count as slivers in every zone, so you can search your library for them, and they trigger ETB abilities as they enter
That's a nice way to keep things in play, but not really an effect to write home about
Your opponent will get a replacement for whatever you destroy, but it will cost you one less mana
Im most likely to play Allure of the Unknown in a Jund deck so that I can also play Brooding Saurian and just get back whatever they cast