Bilbo's Ring

Two costs on one Equipment tells the whole design intent: attach it to a Halfling for a single mana, attach it to anything else for four. The gap is the flavor and the balancing lever at once. On a small evasive creature this thing is a game plan by itself, granting hexproof and unblockability during your turn while turning every solo attack into a drawn card at the cost of a point of life. The "attacks alone" clause is where the design earns its keep: the reward is real, but it forces you to commit to a single threat rather than swarming, and the hexproof only covers your own turn, so the equipped creature is still answerable on the crackback. That combination (protected while it matters, drawing cards while it attacks, exposed when it's your opponent's turn) is a clean piece of tension, and it maps neatly onto the fiction of a ring that keeps its bearer unseen but comes at a cost each time it's used. The lineage here is the long line of card-advantage swords and cloaks, but where those tend to reward a full team, this one wants exactly one hero carrying the load. The steep Halfling discount means the card was built with a specific small-bodied aggressive shell in mind, and it plays very differently in the hands of a deck that has to pay full price to strap it onto something larger.