Depending which mode this can be very easy or very hard.
T1: Select 2 banners
T2: Select 4 banners
T2 Challenge: all 6 banners

Most groups run T1 and choose catapults and inferno as they are the easiest.
Have each tank pick a troll.
They will use single target taunts and drag their respective trolls to opposite sides of the room.
Once they are far enough away have them use their main aggro skills. Once aggro is established DPS on.
All DPS should be on one troll until it is dead.
The troll on the right starts with a melee debuff. (orange flaming shield) This means he is vulnerable to melee but strong against ranged and tactical (-75% inc ranged/tactical)
The troll on the left starts with a tactical/ranged debuff (blue flaming shield) The opposite of the above for this troll.
Depending on your group makeup (most groups are heavy melee in here) The troll on the right is burned down first.
At 400k morale for catapults, the catapults will start launching and remain firing the rest of the fight.
The impact zone is indicated by a large orange glowing circle on the ground. It is helpful to have the red outlines for negative affects on the ground selected.
If you stand in the circle without Stun Immunity you will get stunned and take about a 4k hit.
Do not stand in the circles!!
This is a very heal intensive fight.
Once the first troll is down, all party members focus on the second troll. The second tank should be in full dps mode now (as weak as it might seem it all helps)
About 100k into the second troll, the inferno will begin. Having an RK in each group is very useful for the fire blocker, it really saves the healers a lot of work.
The fire will remain for the entire fight. The fire will obscure the orange circles for the catapults so people need to be very aware of their surroundings.
The fire does about 1k every 2 seconds and remains the entire fight.
Throughout the fight the shields on the trolls will switch, if a group is good enough there will only be one shield on each troll and depending on which you want, you will have that same one the entire fight and DPS really fast.
The switch happens every few minutes but the trolls should not be alive more than a few minutes each.

Most groups take 3 healers for inferno because it can be very heal intensive when the inferno hits.

More on the other banners soon.