Sadly the complication is "skin deep". Thanks to some odd choices when designing defenses, your best bet for survival is piling on as much life boosters as you can muster.

After that it is all about picking up as much damage boosts as you can (again there is some weirdness there because one type of boost is stronger than another kind, and the only way to tell the two apart is by the wording) for how you want to kill stuff.

Yea it's too bad that the actual complication is more an obfuscation of game mechanics. That and the game is quite grindy compared to Diablo2 even if you know what you're doing. A single player version with support for mods could've been very nice. Sadly it's online only.

It's online, but multiplayer/co-op is optional.

Exactly, so unfortunately no potential for modding.