rpg

If the split is going to be a longer term thing, I like to run 1 group at a time and have the players who are not in the split group run temporary characters or NPCs. Usually those are something like MCDM Followers/Companions or just simplified PC characters so that there isn't much of a learning curve, but it just depends on the people at the table.

If the party already has bunch of followers or NPC friends, it's really easy and people seem to enjoy taking the reins of their favorite NPC's for a few sessions. It's also a nice chance for players who like trying our different builds to have a small timeline to try something out with an NPC, and it adds the bonus of shared worldbuilding.

Once the first group is finished, we swap roles and pick up the second group.

Its best to keep this limited in scope, make sure its not more than a few sessions per group, and to only employ it occassionally.

However, if it's only for a part of a session, I go for the A/B storyline in a TV show strategy and tend to verbalize the "camera" a bit more, especially if it makes sense to give some subtle progress hints to the other group so they don't feel the need to worry too much about metagaming. If one group in in combat while the other isn't, I'll switch back to the non-combat group after every round or two. Gives everyone a little more time to get their bearings in a reduced party size and makes the combat action feel a little more intense with some good ol' tension and release.

"OK, as Jimothy unlocks the door and peers inside, it's dark and will take a moment for their eyes to adjust. Swords McGee, watching Jimothy's back, nothing seems out of the ordinary from the perception check, but he does see a flash of orange on the northern wall of the compound where your friends should be at, followed by the distant, unmistakable crack of your allies fireball spell."

"back to the rest of the group, Bobby Fireballs finished up last round by blowing up the guard station, top of initiative, the guard captain..."

It doesn't always go that smoothly, but you'd be surprised how easy it can be once you get in the rhythm of when to change cameras. Its also very important to briefly summarize a hook when changing cameras to transition everyone elsewhere.

If it makes more sense to stay with one party for the entire combat, I'll usually hand over a few monsters to the non-participant players so they have an opportunity to be doing something, if it makes sense.