I would suggest not converting anything you can't get back, even if it's not of any use to you. It's not that difficult to grind for UR's in the first place. Just go beat up on Tea for a while or something. She's easy and DMG's one of her more common drops anyway.
I'm beginner and I'm a bit lost about this farming think. IF I know well, I shall duel against leg.duelist at lvl 30-40 and get high score at the end? Does exist farming deck to reach this goal? And if yes, is there any budget? Coz it seems to me months to get a deck contains more than 4 UR/SR (if i dont have them) My goal to get another Miracle Contect
I think cerberus farm is kind of new player friendly since it's key card is only cerberus that you can get from card trader (you can search the full deck in youtube, there are tons of them)
Cerb is good for farming only a few LDs who dont have much control on the field and just rely on beating sticks! And if i remember correctly Cerb is in the all time available inventory of card trader tradeable every 7 hours or so.