Oketra's Last Mercy

If more than one spell says that lands you control don’t untap during your next untap step, the effects will all wear off during that untap step. You’ll untap lands you control during your untap step after that one.

In a Two-Headed Giant game, Oketra’s Last Mercy causes the team’s life total to become the team’s starting life total (normally 30), but only you actually gain or lose life.

No lands that you control will untap during your next untap step, even lands that aren’t tapped as this spell resolves. This includes lands that enter the battlefield after this spell resolves.