Well, after killing a grand total of TWO lesser demons, I got a red scroll that said I had been chalenged by the Lesser Demon champion. I went to the champions guild to check it out and found out that there was no armor or weapons allowed. The Lesser Demon Champion had two attacks, Mele and Magic which he randomly switched off between throughout the battle.
Heres a picture of the lesser demon champion:

After a very long battle, I finally defeated him, and this is what I got:

A grand total of 1,184 as a reward for using 20+ sharks, a prayer, super attack and super strenght pot. I basically wasted 20 sharks for 1,184exp. So much for this "Great Reward" they promised :\