Technomancer is the workhorse: it enters, mills three, and returns any number of artifact creatures with total mana value six or less straight to the battlefield, so one card can rebuild half a board
Endless Ranks of HYDRA is a sorcery that makes a 2/1 menacing Villain token for each opponent, and it returns to your hand whenever your commander enters or attacks so you can keep recasting it
For example, a normal Art Series version of Zidane, Tantalus Thief is as bulk as it gets, but the gold stamped version has a market price over $3, which isn't insignificant for a piece of cardboard that people often leave laying around on the table after cracking a new box
Most sets have a draft common common or uncommon that can repeatedly inflict one damage on each opponent just by playing other cards, like Firebrand Archer or Erebor Flamesmith
They draw a card at the same time, take a main phase at the same time, attack at the same time, and so on