[MENTION=6801311]KahlessNestor[/MENTION], [MENTION=6855545]Archon Basileus[/MENTION] :
I would make a barricade in O22 that would house the archers and one unit of infantry (defense)
Cavalry would lay with the horses hidden for the moment two squares west in M22 (200 yards shouldn't too much for the cavalry to cross and it makes them hard to see)
5 units of infantry could be 'the bait' lined up in N21 as if waiting for frontal assault, but with hidden 'trip trench' in front of them. The remaining unit should be equally hidden, but so that they can strike from behind (maybe in the chasm at P22) - if that last one is too hard to set up, than leave them with the archers in case of back-attack or as reinforcements to wherever they are most needed (reserve)
Marius would go to 'pull the forces' - maybe cause parts of the group to run in front of the main group in small enough units that Morgrym, Arvana and Marius can handle them. Assuming Morgrym can outrun the group of lizards. This part I'd do like this: Marius goes up front and appears only long enough to shoot something or even just to taunt them. He runs back (similar to the scene with the snake man), Arvana shoots the lead runner (sneak attack) and then joins Marius in running. Finally, they hit Morgryms hiding place. He shoots another one and runs back onto the palisade where he leads the archers and waits for the arrival of the snake or two.