The act of "farming" (or "grinding") is to repeatedly kill a certain level for money, score, or/and rares. Most people in the beginning farm AI3 due to it being easy and fast to kill, and because the electrum reward is enough to let a new player survive -- basically, they're so simple any newbie can farm them effectively if given even the slightest help. "Rush" decks (decks that just concentrate on killing the opponent as fast as possible) do well in AI3. That's the act of "farming" level 3. (As you should have noticed, AI3 = Level 3 = Elder.)
Now, if you mostly want to PVP, there's a deck called grabbow that fares well in PVP1. I'm not going to lie to you, PVP1 is generally easy so any well-done deck can dominate it pretty easily.
This is the link to the "classic" Grabbow (Short for Graboid Rainbow.)
It also does well against AI3, although it is not as good as pure rushes.
If you feel like sharing your entropy deck and want help with it, you can do it in
this board.There is also a PvP deck compilation
here.Last but not least, Welcome.