Overgrown Arch

Most defensive walls buy time and nothing else; this one converts the time it buys into card selection. The 0/4 body stops early aggression cold, the tap-for-life ability grinds out incidental value, and then the sacrifice clause cashes the whole thing in for a Learn. That last conversion is the design logic worth sitting with. Defenders as an archetype have always struggled to justify their slots outside dedicated wall builds, because a creature that cannot attack is a resource you are betting will pay off defensively. Here the wall is never a dead card: if the ground game never materializes, you break it apart into a fresh card and move on. It doubles as a floor and a ceiling, a blocker that refunds itself. Learn is what elevates the sacrifice past a simple cantrip, since it can fetch a Lesson your opponent cannot see coming; when your Lesson bench is empty, the fallback discard-to-draw keeps the ability live regardless. The result is a two-drop that asks very little of the deck around it: no wall payoffs required, no graveyard setup, just a body that holds the line and then turns into gas the moment holding the line stops mattering.