I've personally found a lot of success with Potion of Polymorph instead of Mana Bind. Best case scenario Mana Bind nets you a burn spell, but is really unreliable. Just need to be careful to play Potion of Polymorph AFTER Mirror Entity, unless sheep are your thing. Very good for stuffing Hunter Turn 6 Savannah Highmane, or the big 8/8 quest reward minions.
Copying quest reward spells sounds great in theory, but delaying them with Counterspell is better, and if you really need the 5/5s, or Imps by the the time it's relevant, you're probably already in a bad spot. And if you get Time Warp, you're already dead.