Rethos, Faceless Spy

Rethos, Faceless Spy cannot attack or block unless you have 5 or more cards in your graveyard
When Rethos, Faceless Spy enters the battlefield
name a non land card. Whenever your opponent
plays a spell of the chosen name put the top 4
cards of target player's library into their graveyard.
{4}{u},{t}: Exile Rethos, Faceless Spy then return
him to the battlefield under your control tapped.