Maybe there's a cycle of cards that trigger whenever you play RPS
With strong attacks and big HP, Mega Lucario ex and Mega Gardevoir ex break through boundaries in battle
In addition, I'd put some sort of restraint on her first ability, like requiring you to have x number of cards in y, or banishing a card in both player's Graveyard so that it punishes you for using it too
Kess, Dissident Mage or other commanders which can flashback Approach are good because they let you focus entirely on getting copies to the graveyard, instead of having to hold a couple in hand
The Falsebound Kingdom, Yu-Gi-Oh
Spotting a rare card in the middle of a binder : some little-known cards can be worth several dozen euros without their outward appearance hinting at it