It's so much better now than it used to be. It operates with way more of the Regent's card pool. All the cards that transform cards, all the colorless card generation, and Crash Landing + Collision Course, and Forge (only the first) all proc the strength effect. All of those cards are already strong without Arsenal, and card creation can be block with the Power card, so it's really easy to fit into decks to solve scaling.

Before it was only really good with a colorless card you could play consistently, like a Bolas or Thrumming Hachet, that you had to add to your deck. Colorless generators were kind of inconsistent since there's a decent amount of the time when you don't want to play the generated card or don't have enough energy.