Nowhere, the Realmwalker

Hexproof, Haste, Trample
When Nowhere, the Realmwalker becomes tapped, you may choose to not untap this card during your untap phase.
{2}{b}{g}{t}: Tap target creature an opponent controls. Target creature cannot use activated abilities as long as it is tapped. Target creature remains tapped as long as Nowhere, the Realmwalker remains tapped.
{1}{b}{r}: Sacrifice a creature you control. Target creature an opponent controls takes damage equal to sacrificed creatures toughness.