So let's say you have a blue deck that needs some cantrips to help smooth things over. Naturally you have brainstorm and you reach for Ponder or Preordain and then something hits you: your deck is also running stifles. So you enjoy ending you turn with an island untapped to force your opponent to play around stifle. Therefore you want cantrips that can be cast at intstant speed but is your best option then Serum Visions?
Impulse is probably your best bet. Other than that, Opt