Ender's game option: Enter the portal, go to the king at the tower under guise of joining the parley, or otherwise fight if necessary. Kill or throw (or grapple and jump to the single dragon, depending on mechanics) the king from the tower. Decrypt or otherwise ensure defeat to take over or place the side in stasis. Not only do you defeat the other side, but immediately gain their entire strength without incurring losses to their (now your) strength. Shades of Ansom/Bogroll, and a true 'checkmate' condition.
Doesn't quite sound like what the actual plan is, as Parson was happy about the troops being moved away from the tower (perhaps that was the 'in range of archers/casters' - meaning they moved the casters to the garrison, thus less risky/easier to assault the king?).
But however it works out, it sets Parson up remotely from Stanley in a relatively safe area (post transition), getting him out from under his thumb for a while providing suitable excuses (can't fit on a dragon, won't be allowed to re-enter TMK) for the inability to return quickly/safely, freeing him up for plot purposes if needed (also, jetpack + heavy?). If Parson is the only one truly in-hex there's also opportunity for breaking from Stanley and making another side, say, Hamtopia or Wandaville with a full fighting force, instantly, if necessary for plot purposes.
Speculation is fun. This entire setup has been done masterfully so far, regardless of pace - it's like watching the multiple endings of Clue and waiting to see which is the real one.