Slag Fiend

A one-mana red beater whose size is dictated entirely by what other people throw away. Its power and toughness read every artifact card sitting in every graveyard, friend or foe, which means the body grows fastest in exactly the grindy, attrition-heavy games where a one-drop usually stops mattering. That makes it a strange creature to evaluate: it is a functional 0/0 the moment no artifact cards have hit a graveyard, and a genuine threat once several have. The crucial wrinkle is that it counts cards, not the board. Treasures, Constructs, and most other tokens cease to exist the instant they leave play, so cracking your own Treasures or sacrificing token bodies does nothing for the count; only real artifact cards dying (or being milled, or discarded) feed it. Red rarely gets to field a grow-with-the-board threat for this little without a recurring mana sink, and Slag Fiend's whole pitch is that it asks for one red mana and a graveyard to read off of, then outsources the rest to attrition you do not have to pay for. The cost of that cheapness is total dependence on a public, volatile resource: it is one of the few creatures whose power can collapse mid-combat when an opponent exiles a graveyard in response, so the same shared count that lets it cost a single mana is the thing that can shrink it to nothing without warning.