[spoiler]No problem. I've been crazy busy as well. We hosted a baby shower, and I've been doing some computational modeling for work that I've never done before...
M5 is dead, and assuming Prime/Orson goes along with what I suggested in the last few posts, so is M4. Which means that M3 is the only muskman left standing. Leviathan could reach that one with a charge, or even just a move, so I'll assume you're doing that. The 22 attack roll hits even with just a move.
That 18 is an opposed strength (trip) check, right? And not a touch attack? The attack hits, and assuming that's a trip check, the trip succeeds:
1d20+2=14[/spoiler]The serpentine creature with the girl on its back races across the battlefield, and grabs the remaining muskman's leg with its jagged teeth, pulling its feet out from under it.
With a look of obvious panic on its face at seeing the sudden turn of the battle, it stands up and begins to flee.
[spoiler]New round.[/spoiler]