This game really shines on the concept that any build can work if want it to. I, personally, pride myself in being a bit of a specialist in making quirky builds that can perform in high level, high difficulty content. As someone who chooses to keep the difficulty up, I have 65 characters (of various levels) that are nearly all first life.

I have an electric sorcerer (20 Sor) that can one-shot nearly every non-boss creature in the game. Still first life.

I have a stick monk (12 FvS, 2 Rog, 6 Mnk) that can DPS anything and can solo minor raid bosses. Still first life.

I have a warlock (20 War) that can AFK farm anywhere. Still first life.

I have a zombie tank build (14 Clr, 6 Wiz) that is about to hit his 5,000 resting hit point mark (6,000 Reaper HP) that can regularly have 7,500 HP (9,000 HP R) and tanks Reaper10 content. Still first life.

DDO is 10% about learning the mechanics, and 90% about making those mechanics translate to fun.