On 5 - 19, the easiest way to grind is to not destroy the base and let the Mummy King stack. At that point, they will constantly spawn mummies and can be easily killed with thunder, meteor etc. I gained 40 levels because of this "Exploit". Very fun game!
Bugs. Bugs. Bugs. The final boss didn't even die and I got the victory. Although I like free wins that was just ridiculous. Replayed the level, beat him legit and was still confused how that sort of bug isn't fixed
 "Paladog"){kind=icon}
 "Mighty Knight"){kind=icon}