Discover the Impossible

Look at the top five cards of your library. Exile one of them face down and put the rest on the bottom of your library in a random order. You may cast the exiled card without paying its mana cost if it's an instant spell with mana value 2 or less. If you don't, put that card into your hand.

Mana Matrix

Instant and enchantment spells you cast cost {2} less to cast.

Naiad of Hidden Coves

During turns other than yours, spells you cast cost {1} less to cast.