Act 1 is fighting while undergeared. Getting some gears with lucky charm or thievery will completely destroy enemies.

Act 2 is all about exploring and leveling up your gears to keep up with enemies stat as you unlock source skill. Once you get that level 3 source spell, everything become a breeze even with mages because they have fairer version of Arrow storm.

Act 3 is where mechanics start to happen, a lot. Even with high stat, certain fights won't end unless you fulfill the conditions, like flaming undead lizard people skip will never die unless you kill it once then bless it to weaken it before killing while making sure no necrofire is in vision range.