Combos Utilizing Sands-of-Time

Untap Mana Vault without having to pay 4 mana

Untap Basalt Monolith without having to pay 3 mana

Tap opponent's creature and then destroy it with the assassin.

sands of time makes all of these inexpensive artifacts untap during your upkeep. if you have a time vault, then you have an infinite turn combo.

sands of time untaps monolith for you so you don't have to

Put a Betrayal on two of your opponents critters and draw an extra card every turn

since players skip they're untap steps - it's possible to make all of your oponent's lands (of the chosen type) phase out, and never phase back in!

turnabout untaps opponents lands at end of your turn. then, during opponents upkeep, sands of time taps all their lands, and then power surge deals it's damage.

play equipoise then sands of time and there stuff can't phase back in

play the time vault and sands of time. the next turn time vault gets untapped and sands of time gets tapped. play another sands of time and take the extra turn. -> infinite number of extra turns