Complex sentence: The effect of the card pass is that an identified card is inserted somewhere into a deck, however following rapid and concealed manipulation by the performer, it is then revealed to be on the top (or bottom) of the deck.
Split into simpler sentences: The effect of the card pass is that an identified card is inserted somewhere into a deck. However, following rapid and concealed manipulation by the performer, it is then revealed to be on the top (or bottom) of the deck.