I think it doesn’t have to be scripted, position the ancients behind or close to the bandits or NJ soldiers should do it. The mission to get the Synedrion bionics with Synderion defenders and Pure works almost this way and I think this is not a bad example how to go.
Map design and positioning, that’s IMO all to get there.
Edit (I should read the whole post before writing ):
If this is in the game, then it would be probably the best solution.