Modern Masters

Dampen Thought

Target player puts the top four cards of his or her library into his or her graveyard.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Target player mills four cards.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Champions of Kamigawa

Target player puts the top four cards of his or her library into his or her graveyard.
Splice onto Arcane {1}{U} (As you play an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)