After thinking about it some more I could have a major good npc that is going to be helping the PC's. I wanted to save him for later but it might have to be now.
Or I could have a good npc group that was tracking that bad npc group
If there's a knight shining armour to save them then why not just wait and let him fight the battle. It seems as though you've designed a challenge for your players and you don't believe they can cut it as heroes?
