If the top card of your library changes while you're casting a spell, playing a land, or activating an ability, the new top card won't be revealed until you finish doing so.

The top card of your library isn't in your hand, so you can't suspend it, cycle it, discard it, or activate any of its activated abilities.

When playing with the top card of your library revealed, if an effect tells you to draw several cards, reveal each one before you draw it.