Well Me and my friends found this hole too but this is what we think:
Since it is a Combat Phase (with in the Interaction Phase) between two players, each player will take turns playing combat cards, starting with the party with the higher speed total(roll the die for ties). Then both players take turns playing combat cards until they cannot. Then calculate total Combat Abilty and proceed with rolling the die for combat conclusion. I hope this helps ill put it into bullet form so its more clear.
- Declare Combat against an opposing party
- -Now considered Combat Phase- (But still in the Interaction Phase)
- Check total Speed Value and compare who has the highest total.
- Party with the Higher speed acts first and plays a Combat card.
- Opposing Party may play a Combat card
- Repeat the past two steps till both players cannot play cards anymore, the proceed to next step.
- Calculate total Combat Ability Scores and Roll Die for combat conclusion.
- Conclude Combat Phase
When ever you play a Combat Card the effects resolve immediately. Interruption Cards CAN still be played during these Combats.
I hope this helps. But remember when you play a Combat cards keep them visible and do not discard them till the Combat is over.