How do you build an army in Game of Thrones: Dragonfire?

An army is 3 dragons across 3 positions: Left Flank, Center, Right Flank. All three share a single troop type (one for the whole army). And you can field up to 5 armies at once.

The recipe that works:

• Pick the troop type first (the one you've researched the most).
• Put your best aura dragon at the Center (the Center spreads its aura to the whole army).
• On the flanks, place dragons that are green for that troop type (+20% stats).
• Fill troops to the max on every dragon: that's your fuel.

Don't think "3 strong dragons", think "1 troop type + 1 central aura + green affinities lined up behind it". That's what makes the difference.