building on tsugaroo's idea, i played the first level
immediately after the battle starts attack straight from your starting point to the enemy starting point and then send another wave of attackers to the empty base right in front the the enemy start point. this is location that the enemy will attack first
do it right and the battle ends in seconds.
i started when i got the blind bonus and in less then a minute i got both the sudden death and no magic bonus
if you activate all 3 you get around 10000 xp in just a few seconds!
+ this if it works for you