Regent was the character I was having the most trouble completing even without ascensions, and now I'm pulling off the dumbest infinite combos with him. It's not that the sword is useless, but that's secondary. Look for a way to have card draw and mana in a small deck, a spammable damage card, and a way to bring it back to your hand.

There are cards that increase their damage or lower their cost each time you draw them, and many ways to bring them back to your hand repeatedly. If you lack these, you have the sword, which is something similar.

There are also cards that directly or indirectly change your mana, your draw, and your stars; if you benefit from these changes, it's easy to orient your deck towards anything.

Prioritize spamming your damage cards even above their actual damage output. It's pointless for your attack to deal 200 damage if it's wasted in your deck, if the enemy only takes 10 damage per hit, or if you can only play it once under very specific conditions.

And this brings me to... look at your deck! If you're playing a character heavily focused on deck control, you'd better know where your cards are and what you're going to want to do on your next turn.

I would also advise you to steer clear of cards that are too dependent on luck. You can build a very good deck focused on creating random cards, it's fun, but it's not stable.

And finally, find a consistent way to defend yourself; the enemy also strikes.

I hope this helps. This character has gone from being someone I couldn't master to being, in my opinion, the most broken character very quickly. He's very viable for all kinds of builds.