ANOTHER TIP:
1)Wait for epic energy to reach 10 (max)
2) Attack with 2 knights + 2 friends attack (7 energy)---(3 left)
3)Wait till 3 epic energy regenerates (6 energy)
4)Main Knight + 2 friends (6 energy)

Requires person to be active as for 3 energy to regenerate it takes about 1h45mins. Meaning u have only 15mins left to attack Epic boss again.

~This method can get u 5k-13k more damage. (5k being for low lvls 13k+ for high lvls)