Hi there, welcome to the forums! Arena is asynchronous pvp-- you face decks that other players have made that have special perks and bonuses. This means that facing the arena is pretty much like facing a regular AI, but that AI has higher rewards. In addition, arena decks lose HP over time to encourage new submissions, so you'll often find lower-than-normal HP decks in bronze and silver where there aren't as many players submitting decks. More on that
here. Ah, to answer your question: Yes, try the arena! Barring lucky spins, it has generally higher rewards than AI4.
One thing to note: this particular thread isn't the best place to post questions. We have a special thread for questions
here-- Also, feel free to PM any of the mentors listed in the
OP of this thread. If you want help in real-time,
chat is the best place. There's also the
deck help section if you want help on a specific deck! And if you're looking for more ideas, there's
this wonderful compilation of decks, as well as the tutorials I linked in your introduction thread.