They look for the most dramatic, most well-documented, and most visually impressive errors regardless of age, and they pay close attention to the underlying card's standalone market value as a baseline for the error premium
Nothing changes in terms of blockers I dont get to retroactively fly over my opponents creature at this point, so they wont take any damage
Cards like Tempered Steel that buff your artifact creatures are great
these effects are fairly expensive and generally sorcery speed, so cards like Swan Song and Counterspell are perfect answers
You could cast a creature with flash to block your opponents attack, or even cast a creature on their end step that can win the game the following turn
Most importantly, its the most affordable for those who want to slot this into a deck