As for Collector's Cage, its main role in the deck is to cheat in Overlord of the Mistmoors
5) BelleAccomplished Mystic (New Enchanted) Our first pick is actually an old card with a new coat of paint
Exiling two target permanents (any permanents) is a nice way to turn a game around, and even if your opponent can keep chumping it, Ulamog will just mill them out in a couple of swings, anyway
However, you must be cautious when doing this, as there is much more conscious thought involved with this method than there is when using another method of shuffling
Unless you have additional synergies with Clues, they arent the best payoffs since you need to pay two mana to use them
But at 4 mana and tapping, I would only be turning to this as a last resort after exhausting all the other discard effects