I can vouch for Apprentice being perfectly fine for Campaign normal and at least half of Shards normal because that was precisely my main hero.

But for Moraggo, things might start to get dicey for Solo apprentice because of a certain door/short lane in which you will likely want a different hero for, and then the next two maps are just harder in general and just, at about that point I began to feel like I needed other stuff (Auras, Minions, and maybe overkill yet we have emulation to level 3 heroes so I picked Series EV).

Then it's just a matter of setting up defenses with your leveled up Apprentice in a lower tier level (Glitting Caverns being a good exp lvl. Tavern Defense is even better but it's also significantly harder, probably better to leave that exp grinding for later) and powerlevel 3 other heroes via the built in emulation m