There is a formula, just as tricky as the battle. You can find the whole post here
Here a "short" summary/explanation:
A basic camp has a number of hitpoints: 250hp
If you win, you end the battle with a general (of course) and let's say, 5R, 1S and 50XB.
Your countdown time is based on how much different troops you end the battle, so 50XB will be changed to 1XB, and 5R will be changed to 1R, and the 1S will still be 1S.
Now you have this:
G: 120 attack damage
R: 15-30 attack damage (80% max damage chance)
S: 30-40 attack damage (85% max damage chance)
XB: 45-90 attack damage (80% max damage chance)
Camp: 250 hitpoints
Now, this will be a battle like we beaten those enemy's inside the camp, in best case:
Camp: 250
G strikes (-120)
Camp: 130
R strikes (-30)
Camp: 100
S strikes: (-40)
Camp: 60
XB strikes: (-90)
Camp: 0
The camp is destroyed in 1 round
Now in worst case:
Camp: 250
G strikes (-120)
Camp: 130
R strikes (-15)
Camp: 115
S strikes: (-30)
Camp: 85
XB strikes: (-45)
Camp: 40
The camp is not defeated in 1 round, so we need another:
Camp: 40
G strikes: (-120)
Camp: 0
The camp is defeated in 2 rounds
This means, the destruction times are: 1-2 rounds
Check this and you see it's exactly what I said.
Note that it's only a small chance for 2 rounds.
What if we win with only 50C left?
No problem:
Camp 250
G strikes: (-120)
Camp 130
C strikes: (-5 or -10)
Camp 125 or 120
round 2:
G strikes: (-120)
Camp 5 or 0
C strikes (-5 or -10)
Camp 0
As you see, even with the troops with the lowest damage, the camp is always destroyed within 2 rounds
All camps works the same, the only difference is the building, here a list of it:
Code:
Building Damage
Bandit camp 250
Watchtower 1000
Reinforced T. 1500
Stone tower 2000
White castle 2000
Witch tower 2000
Bone church 2000
Dark castle 2000
Is this all you need Tage?
What we can use here, is in the attack to the leader, you can just take an extra M, S or E with you, it will reduce the countdown time If it wasn't already in your party of course