Rune of Speed

A two-mana Aura granting +1/+0 and haste has no business seeing play: the buff is too small, and the tempo hit of a targeted enchantment too large. The enters-the-battlefield cantrip is the fix, recasting the whole card as "a permanent buff that replaces itself." You are not spending a card to make a creature marginally bigger; you are drawing a card and taking the buff as a rider. That reframing is what lets a stat line this modest exist on a spell at all. The second clause does the subtler engineering. Because the Rune enchants any permanent rather than only a creature, it can sit on an Equipment and lend its bonus to whatever holds that gear, surviving the death of any single creature. Haste on an Equipment Aura is the genuinely strange wrinkle: gear that grants immediate attackers to freshly cast bodies, laundering summoning sickness through the equip step. Throughout, the cantrip carries the card, papering over the fundamental weakness of a permanent-based combat trick by making it cost nothing in the aggregate. It is an object lesson in how a replacement-draw clause can rehabilitate an effect that would otherwise be unplayable, and the modularity between creature and Equipment targeting is what turns the broadest possible enchant clause into an asset rather than filler.