Belbharhun Slave Bringers

Insidious - {b}{r} ({b}{r}: Exile this card from your hand. You may cast it for as long as it remains exiled.)
When Belbharhun Slave Bringers enters the battlefield, if it was cast from exile, you may put a creature card with converted mana cost X or less an opponent owns in exile onto the battlefield under your control.
Whenever another creature is exiled, you may exile Belbhar