sages of the anima locks draw step
Sages of the Anima reads that noncreature cards in the top three go to the bottom of my library, but MTGO only gives me the option to keep them on top, so every draw step I eventually am just seeing the same three cards (and not drawing them!)
Having a "Sages of Animar" in play and trying to draw a card after the first reveil where 3 noncreature cards. The reveiled cards are either put back on top of the libary and then reveiled or "Sages of Animar" reveils them from the bottom of the libary. Either way reveiling the same cards again and again for every draw means that the player has no chance of drawing another card for as long as "SoA" remains on the battlefireld.