Norn's Seedcore

Chaos on arrival is the whole trick here. Most planes make you roll the planar die and hope for the chaos symbol before their effect fires; this one guarantees a chaos trigger the instant you walk in, and that chaos ability is a search through the top of your planar deck until it turns up another plane and walks you there. The clause that makes it sing is the instruction not to planeswalk away from any plane: you arrive, you resolve the walk-to, and you end up on the freshly revealed plane while the effect chains from a plane you technically never left. In practice it is a planar-deck accelerant, a way to skip past dead cards and land somewhere useful without spending a die roll, and its zero mana value keeps it purely a creature of the planar deck rather than anything you cast. For a subgame built around the randomness of the die, it is a rare piece of deliberate steering: a plane whose entire function is to push the planar deck forward and put one link of the walk under your control.