To restart the turn, start with the most recent game action and undo it, then repeat this for each game action taken this turn in reverse chronological order.

If any cards are put into a library to undo an action, and they weren’t known to have moved from a certain position in that library, randomize that library after doing moving those cards.

Any damage undone this way doesn’t count as life gained. Similarly, life gain undone this way doesn’t count as life lost.

If any game actions involve randomizing a portion of the library, randomize it again to undo that action.

While restarting the turn, no abilities can trigger. Abilities trigger when something happens, not when something unhappens.