So, in playing around with the different leagues and looking for an optimal farming solution, I've hit on a deck/league combination that works well to make decent money and have a good chance at fetching those rare spins. Strangely enough, it's a deck that I learned in secret from JMiZzle7 a long long time ago for t50 farming. It just happens that modern Silver League is very much like the t50 of a year or so ago, and the same tactics that kicked t50s ass back then work over Silver League very well at the moment.
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6qq 6qq 6qq 6qq 6qq 6qq 6tt 6u3 6u3 6u3 6u3 6u3 6u3 71b 745 74f 77g 77g 7ai 7an 7dl 7dq 7gv 7ju 7n3 7q5 7q5 7t9 7t9 80b 8pj
The beauty should be immediately apparent to all observers. Full credit to jmizzle, I think I modified one or twos card to make it perfect for Silver League.
Edit: after winning 3 rarespins in Gold League out of 20 games, I added the [Gold League] tag to this as well because I figure anything speedbow-y that has a 50%+ winrate in Gold League is probably doing pretty well.
[edit]Update: Works 150% better for Gold with -1 Graboid, -1 Archangel, +1 Pulverizer, +1 Crusader. Very worthwhile changeup.[/edit]