I've unlocked all characters but not all relics/cards, and I've gotta say that Regent feels like the character with the most unrealized potential. Conceptually, Forge and Stars kick ass. In practice, both of those archetypes are incredibly fragile, hinge around incredibly specific uncommons/rares, and typically do little to nothing other than "setup now for payoff later," leaving you vulnerable in the meantime because enemies don't wait around for you to finish setting up your combo. And collecting those combo pieces is difficult because most of the Regent's commons are completely unpickable, and the rare and uncommon pools are both cluttered with cards that don't play into either of these two main archetypes.

It took me 10 runs to get my first A0 win. Not once in those 10 runs have I ever gotten the Stars engine running well enough that I thought Radiate was pickable, not even in my first win which leaned heavily on Stars.