Ariane, the Labrynth Servant

Vigilance.
You may discard an instant card. If you do, search your library for a Labrynth creature with converted mana cost less than or equal to this card's mana cost and put it onto the battlefield. Then shuffle your library.
Whenever a creature leaves the battlefield due to an instant card effect, you may draw a card. Then, each Labrynth card in your hand and command zone gains "This spell costs {2} less to cast." This ability triggers once each turn