In the case of the former, its because the best choices vary not only by color identity, but often by specific deck building limitations: Seismic Assault and many other red effects want you to play an extra-high land count, while a black deck with reanimation and Tortured Existence obviously cares about discarding creatures
When you discard a card this way, Serum-Core Chimera deals 3 damage to target creature or planeswalker
It does work quite nicely with pump spells though, so that might be a nice combo to help you draw a ton of cards
After all, they didnt want to reprint cards that had broken Standard, like Strip Mine or Tolarian Academy
Laurine, the Diversion Laurine, the Diversion is a 3/3 with first strike and a clean activated ability: sacrifice an artifact or creature to goad something
It helps that this deck has a surprisingly high mana curve , with lots of expensive spells to cascade off of