Sacred Armory

A pump engine with no off switch, which is exactly the kind of card the core sets used to print as deliberate filler. The repeatable +1/+0 has a long lineage going back to the cheap "firebreathing"-style activated abilities, but stripping the effect onto a colorless artifact rather than a creature means anything that survives the turn keeps the engine, and any deck of any color can run it. The trouble is the math: paying two for a single point of power is a terrible exchange in a vacuum, and the only way to make it worthwhile is to sink mana into it across multiple activations, which is precisely when you most want that mana doing something else. What the card is actually built for is a board that has already stalled, where attackers can't profitably trade and the extra reach is worth more than tempo. As a piece of fixed value on the battlefield it dodges the usual problem with combat tricks (you don't have to draw it again), but it asks for a mana surplus that aggressive decks rarely have and slow decks rarely want to spend this way. It fills the role of a low-rarity finisher for a creature deck that has run out of cards but not out of lands, and not much else.