Select an enemy follower on the field and destroy it. Spellchain (10) - Deal 3 damage to its leader. (If you have at least 10 spells in your cemetery, excluding this card, perform SC (10).)
QCan spells such as Night Horde and Fiery Embrace be played when there are no enemy followers on the field that can be selected?
ANo. If the card text explicitly instructs you to "select" a target, and there are no cards that can be selected, then you cannot play the card or pay any associated costs.
QIf there are no enemy followers on the field, can I still play this spell to deal 3 damage to an enemy leader?
ANo. You must be able to select a follower to play this spell.