Each type of Expert is also getting their own combat move. Subterfugue gets Backstab, Survival gets Ambush, Knowledge gets Calculated Strike. I was working on the move for the Communication Expert and decided to see if I could use the Turn Undead table.
The move is Harangue Enemy, and the idea is that the Expert in Communication (a Bard, or Siren, or firebrand Preacher, etc.) would be able to speechify a real whammy on a group of creatures. The possible results are Flee (in which case they will continue to be a threat, but later), Surrender (which brings with it logistical issues), or Join (you made some converts, and now have extra henchmen).
There's still some details to work out, but since people are thinking about this sort of mechanic, I thought I'd throw it out there.
Compare the Expert's HD to the target's HD (3 HD could be one 3 HD creature or 3 1HD creatures), and roll 2d6.
Note that, unlike the Turn Undead table, nothing ever becomes automatic. It's nice to roll dice in a dice-rolling game. Some of the numbers dip down below what can naturally be rolled on 2d6. This leaves the GM with room for adding negative modifiers based on environment or circumstance.
Oh, and of course you could just play around with the Reaction Table, but I like that this gives the Communication Expert a distinctive mechanic to call their own.