Say you are playing against a Sylvan deck, and your opponent has just Set a monster (so, it's very likely either Merchant or Komushroomo) AND a spell/trap (most likely a Divine Providence). Which one do you go for with your Emperor's effect? Allowing the monster to get flipped can be devastating, but Divine Providence can also prevent your Emperor from being special summoned from your graveyard through CotA, and can also be used to destroy your Emperor the next time it uses its effect when special summoned from the graveyard.
Target set monster, search with pandemonium when emperor gets blown up, and then hope they don't mill a marshleaf next turn. If call of the archfiend stays on the field then the emperor can swing his dong around with no problems.
Anonymous No. 2
Anonymous No. 2