Beat the diablo clone on normal, the secret dungeon aint that hard and a great place to level. But the champion there is again waaay better the diablo clone..
Woops I see some1 already answered by question.. beat the insane dungeon, but no fake diablo yet, it's random i guess. Ill look again tomorrow it's getting late :P
For sparta, take the grenade launcher and upgrade to max. You can launch volleys of 9 grenades quite fast after one-another. Spend the rest on alot of gunman and some wall if you want though you probably won't need it :)
 "Death vs. Monstars"){kind=icon}
 "TextRPG: The Rise of Diablo"){kind=icon}
 "Storm the House 3"){kind=icon}
 "Pillage the Village"){kind=icon}