Emry, Lurker of the Loch

The whole card is a bet that your artifact count is high enough to make three mana a lie. Affinity does the pricing: cast her into a board of cheap artifacts and she can land for a single blue, since Affinity only chips away at the generic portion of the cost. But the mill-four on entry is what turns her from a discount body into an engine, because it isn't card advantage so much as inventory. Every artifact that hits the yard becomes recastable through the tap ability, so the mill is feeding the machine rather than thinning a deck at random. That reframes the recursion: you aren't looping one artifact, you're building a graveyard of options and dealing them back to yourself one per turn, paying full cost each time. The tension is the 1/2 body against the tap cost. The ability fires once per turn and demands the creature survive and stay untapped, so she rewards a board that protects her and punishes decks built to answer a single fragile Wizard. That per-turn tap is the ceiling on her fairness: the recursion is a steady drip, not a loop, unless you pair her with an outside untap effect to fire the ability again in a single turn. That is the seam that separates the value engine from the combo piece. On her own she sits at the exact intersection of the affinity discount and the artifact-recursion archetype, which is why she reads as fair; hand her a way to untap and the same tap ability becomes an engine that only stops when your graveyard runs dry.