Merieke Ri Berit

Merieke Ri Berit doesn't untap during your untap step.
{T}: Gain control of target creature for as long as you control Merieke Ri Berit. When Merieke Ri Berit leaves the battlefield or becomes untapped, destroy that creature. It can't be regenerated.

Nihiloor

When Nihiloor enters, for each opponent, tap up to one untapped creature you control. When you do, gain control of target creature that player controls with power less than or equal to the tapped creature's power for as long as you control Nihiloor.
Whenever you attack with a creature an opponent owns, you gain 2 life and that player loses 2 life.

Debt of Loyalty

Regenerate target creature. You gain control of that creature if it regenerates this way.

Preacher

You may choose not to untap Preacher during your untap step.
{T}: For as long as Preacher remains tapped, gain control of target creature of an opponent's choice they control.