"Epic Frameskip" is back on it's 4th edition.
Points to consider:
1- There is, technically, few stuff that can be considered really "new".
2- New spell system (mana, instead of individual CDs) rocks.
3- Normal levels are easy (just click "assault"); Hard levels are moderate (Click "assault" and cast a few spells); Epic mode is ALMOST IMPOSSIBLE because there's a boss dude/gal with tons of HP and attack.
4- Grindfest requires ALL MAXED UPGRADES. This requires lots of gold, which in turn requires lots of farming, which is return requires lots of time. I recommend grinding on easy levels and doing something else in the mean time.
5- Baal was kind of a let down. Well, that's why he's "tricked", not beaten.
6- To avoid frameskip/lag, just move the battle window around, away from combat.