Rust Elemental

Flying
At the beginning of your upkeep, sacrifice another artifact. If you can't, tap this creature and you lose 4 life.

Amoeboid Changeling

Changeling (This card is every creature type.)
{T}: Target creature gains all creature types until end of turn.
{T}: Target creature loses all creature types until end of turn.

Bill Ferny, Bree Swindler

Whenever Bill Ferny becomes blocked, choose one —
• Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
• Target opponent gains control of target Horse you control. If they do, remove Bill Ferny from combat and create three Treasure tokens.

Bronze Bombshell

When a player other than this creature's owner controls it, that player sacrifices it. If the player does, this creature deals 7 damage to the player.