There are 2 ways of copying card effects.
You can clone the card by using the Copy card to game link from the cards's list "more admin" dropdown menu. This will create a duplicate of the card in your game.
You can also open up the effect builder for the card you wish to copy, and on the bottom buttons click on "code view". This will open up the text format of the effect builder code which you can copy and paste into another card's codeview, overwriting it.