This is the deck i use for grinding arena gold. It's a pretty big deck, but one of the most common ways of losing with it is still drawing yourself out, as you can draw a lot of cards with sundials and hourglasses.
The only decks i have big problems with are the mono aether with shard of wisdom and to some extent the shard of freedom decks (if i can't draw into the pulverizer quickly).
The basic idea is to win with the Dune Scorpion poison applied with Unstoppable, meaning you can ignore all shields and creature removal, as you only need to hit them once.
The deck is quite slow, but it will consistently win 3 matches in a row, netting you an upgraded weapon/shard spin. And it often wins with full hp giving about 250 electrum.
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4vj 4vj 4vj 4vj 4vj 4vj 5rp 6qq 6qq 6qq 6qq 6qq 6qq 6qq 74a 74a 74a 74a 74a 74a 77f 7gq 7gq 7q0 7q0 7q0 7q0 7q0 7q0 7q0 7q5 7q5 7q5 7q5 7q5 7q5 7q8 7q9 7q9 7q9 7q9 7q9 7qd 7qd 7qd 7qd 7qd 7qd 7ri 80d 80d 80d 80d 80d 80d 8pu