This battle will be tough, because bluffing or not there still are 500 Soldiers a Kilometer away from Gaster Kingdom, this amount can easily overwhelm Gaster Kingdom's Army of 130 Guards.
This points out towards the fact that the four Fire Blasters can't mess up, they will attack the enemy Army from each side. To increase the odds of success they need to shoot down as many people as possible once they officially start the attack because after it success will be solely dependent on Gaster Kingom's Army.
So an hour later, with the plan rehearsed and repeated so the odds of messing it up are slimer, the four Fire Blasters with King Michael included have tip toed their way towards the Army.
Of course the Fire Blasters are invisible at the moment, since four people standing against them from four sides will come as threatening. The enemy Army constantly murmuring helped to deafen the sound of their footsteps, it also allowed them to move freely.
