Sentry Oak | Illustration by Warren Mahy This isnt really a broken space, as the only ways to get around the restriction on walls and defenders attacking are printed on cards that explicitly let you do that
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2 Wall of Roots, Vine Trellis, Sylvan Caryatid, and Overgrown Battlement History has shown that a 2-drop Wall that accelerates your mana while providing a strong roadblock ends up being something in Standard
10 Refurbished Familiar One-Mana Forced Discard Although Refurbished Familiar costs four mana, more often than not, you'll be casting it for much less, usually just one black mana
With four of these in your arsenal, you could mill almost half of your opponent's 60 card deck, and for a low cost as well