Also black screen bug. It says plug in blocked when I load the page, but flash is enabled and I pressed the "allow all plugins this time" button. Still no luck. This also happens with other pages that use NPAPI/Unity, so not sure if this game is using that.
I beat all the game extra monsters at level 15. Easy win techniques:
1) Become spellcaster, get pyroblast and cold blood. Activate cold blood and then start casting pyroblast to do crapton of damage in 3 turns. One hit KO for almost any basic monster and they can't kill you in 3 hits.
2) For stronger monsters, get polymorph, pyroblast, cold blood, and adrenaline rush. Polymorph them, activate adrenaline rush, then coldblood + pyroblast. After pyroblast hits, you can use frost nova then eat magic dust. Use attack after frost nova if more than 45 energy left. Rinse and repeat the frost nova, magic dust, and normal attack until dead.