Revelahk, Isle of Worship

Revelakh, Isle of Worship enters the battlefield tapped.
{t}, Tap an untapped creature you control: Add {u}{b}, add {b}{r}, add {u}{r}.
{t}, {x}, Sacrifice Revelakh: Put the top X cards of your library into your graveyard.
Drifting through the Blind Eternities, howling to an unseen force.