I find the approach of using the Council rules (in fact, a form of Extended Tests rules) to play out a battle very interesting.
The scene will most likely become very narrative, instead of a clash by clash number counting, and that can be very good indeed.
The first ideas that come to mind, is that the Introduction step might be sort of a Deployment phase: one hero acts as the field captain (or some other fancy name) and decides how the Free Peoples army positions itselfs in the battleground. A Battle test would be handy to gain the higher ground, etc, but also Stealth might be useful if the heroes plan on ambushing the enemy, Hunting if the adversaries are animals (spiders, wolves) or even Explore if the terrain would allow for narrow passages or routing maneuvers that could add surprise movements. In the end, the test would simply add to the Time Limit (as the Introduction does in Councils), but narratively it could work very differently in one case or the other.
During the Interaction, my take on mass battles has always been to prepare some vignettes beforehand of combat situations and present them to the players. Then, let them decide how to handle them and choose one hero to make an appropiate roll. For example, in Round 1, the heroes spot (no need for an Awareness or Scan test) a small group of enemies taking a detour to attack the fort they are in from another -less defended- angle. But, if they leave the front door, the main enemy force might take the gates down. What do they do? Choose a test that represents the tactic they propose, count the successes, and move on to Round 2, where you should present them with another vignette. Try to link the new scenes with the outcome of the former ones, of course. If they let the small group act freely, focusing on defending the main gate, the next scene should imply that skirmirshing group being able to throw grapples at the wall and climbing to the top of it, for example.
Something else I think would fit Battle Rules would be that, after each round (each vignette), the heroes should gain an amount of Fatigue and maybe Shadow. Battles take their toll physically and mentally. I'd avoid adding more dice rolling (things like Athletic or Valour tests to reduce the amount gained), but would base the amount on the outcome of the test rolled by the hero who confronted the vignette. Much like the Fatigue gain during Travels, based on the Role affected by the Hazard. So, maybe, after each round of combat, each hero will gain 3 Fatigue points and 3 Shadow points, reduced by 1 for each level of success from the previous test to solve the vignette.
Let's see what other ideas can come up here, but I generally think that mass battles in TOR should use the basic structure of Extended Tests and Councils, not extremely new rules.
By the way, here are the Battle Rules I wrote for the 1st Edition. Maybe some ideas might come handy:
https://docs.google.com/document/d/0Bzk ... ue&sd=true
EDIT: Added idea about gaining Fatigue and Shadow after every round of Battle.