Ok so I checked and checked and we have a ruling on Combo Strike.
Starting on the Warmachine Forums I find this:
First, Let me introduce your Rules team for this forum. We call them the Infernals.MacallanLunatic CalmNot DicePoeticruseHaightMaudlinMootazThese fine soldiers of the shadow are here to answer your question and help you resolve any issues you have with the rules. Their words are official.
Next we go to a thread on combo strike and find the two posts that essentially end the discussion.
http://privateerpressforums.com/showthread.php?t=2796&highlight=combo+strikeRead the last three or four posts.
The answer by Lazlo...
While no one I know that's played the game for a while has been confused by Combo Strike, I do know new players that have been. And it boils down to this...Combo Strike says, "Instead of making a normal damage roll, the POW of the damage roll is equal to this model's STR plus twice the POW of this weapon."On page 50 of Mk II Prime, under the MELEE WEAPONS section it says, "Melee Damage Roll = 2d6 + POW + STR"The problem is the overloading of the term POW. Going strictly by the rules, we get the following:POW of Combo Strike = POW of weapon x2 + STRSo the damage roll would be 2d6 + (POW of weapon x2 + STR) + STRCombo Strike should say something like the "P+S of the attack", rather than "POW of the damage roll". Or that the POW of the damage roll is equal to twice the POW of the weapon, and leave the STR part out (since it is already defined as being part of the melee damage roll).Then the response by Lord Hedrahil...
Thanks Lazlo!!you understand my question...So...Instead of POW it, would sai P+S, is that correct?Then Lazlo responds...
There might be a clearer wording, but essentially yes.All that's changing in the Combo Strike is that instead of getting multiple initial attacks you only get one, and you add the POW of the weapon twice instead of just once to the damage roll.So a STR 8 model with two POW 4 weapons and the Combo Strike special attack (* Attack) would have the options of:a) Two P+S 12 attacks, orb) One P+S 16 attackAnd after all that, the MOD MACALLAN whose word is considered OFFICIAL says this...
I think that you are all on the same page.To Sum up:So it is Strength of model + POW x2 (each weapon) +2d6. That's all she wrote!
Hope that helps us for our next games!