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.
Near Mint - $4.25
Near Mint Non-English - $4.25
Lightly Played - $4.25
Lightly Played Non-English - $4.25
Moderately Played - $3.50
Moderately Played Non-English - $3.50
Heavily Played - $2.75
Heavily Played Non-English - $2.75
Damaged - $2.25
Damaged Non-English - $2.25