Sands of Time | Magic: The Gathering
Formats Sands of Time is Legal in
Official Oracle Text for Sands of Time
At the beginning of each player's upkeep, that player simultaneously untaps each tapped artifact, creature, and land he or she controls and taps each untapped artifact, creature, and land he or she controls.
—"Love Song of Night and Day"
Official Rulings for Sands of Time
8/1/2008 : Skipping the untap step means that phased out cards won't phase in, and permanents with phasing won't phase out.
10/1/2009 : You can tap lands for mana before Sands of Time toggles your permanents. The mana you gain is in your mana pool during your upkeep step, but will disappear before your draw step if you don't spend it. You cannot save it to be spent on the card you will draw this turn.