Arianna, the Labrynth Servant

Whenever this creature enters the battlefield, search your library for a Labrynth card, reveal it, and put it into your hand. Then shuffle your library.

Whenever a creature leaves the battlefield due to an instant effect, you may draw a card. Then, all Labrynth cards in your hand and command zone gain "This spell costs {2} less to cast." This ability triggers only once each turn.