Similarly, if you control more than one Promise of Tomorrow, they will each trigger at the beginning of the end step if you control no creatures. These abilities can be put on the stack in any order, and the first one to resolve will be sacrificed and return cards to the battlefield if appropriate. The next ability to try and resolve will check to see if you control any creatures at that time. If you do, the ability won't resolve, Promise of Tomorrow won't be sacrificed, and it won't return any cards.