Orc Bikes harass the Space Marine forces as they appear. Meanwhile an oversized Killa Kan takes up a defensive position on a hilltop.
While the Orcs are focused on the frontal assault an Assault squad deep strikes close to the Orc fortified position and takes cover. The Orcs open fire with everything they have and the Marines take a couple of casualties. Reacting to the fire (as a fast unit) they charge into the fortified position using their jetpacks. In the ensuing melee the Orc squad is put to the chain-sword.
The following move saw the Killa Kan destroyed and the objective taken.
From this battle I ended up making two changes and updated my grid based rules.
Firstly, I have worked out how to differentiate between a flamer (hand held) and a heavy flamer (vehicle mounted). A flamer is of medium impact and can ignore personal armour. Therefore will continue to be effective in assaulting troops, but will require a 6 to cause a vehicle or monstrous creature to take a saving throw. While a heavy vehicle mounted flamer will always be high impact.
The second modification was to vehicle overruns. All vehicles can overrun and roll a D6 minus 1 from the score for casualties. Similar to a blast weapon. In the case of light vehicles the hits are low impact, with medium vehicle causing medium force hits and heavy vehicles high impact hits.