How do I decapitate the enemy force?
I think in this case, that the phrasing "decapitate" is more a metaphor than an actual skill. I haven't found a unit that has a skill named that, so I don't think that is the case.

Additional, i dont fully agree with the claim. Yes, you could to some heavy start nuking with some combos, but then it's a question of counterplaying it in your own lineup.

A lineup poised on striking fast and hard often have little room if they dont succeed in that first strike.

Having said that, some characters and units in Diskwars ARE a bit out of balance, but that's just my opinion.