During your Draw Phase, before you draw: You can declare 1 type of card (Monster, Spell, or Trap)
Constructed is a very different story, so a mechanic centered around casting 2/2s for 3 is an extremely tough sell, but there have been a few highlights
It had some minor other notes to play, such as being part of the theoretical Extended Yawgmoth's Bargain deck I was asked to build to show how often it could kill on turn one, and providing the method of execution in some other cases, but Cadaverous Bloom is all about the Prosperous Bloom deck
So only a few real-world games are known to have non-trivial complexity
You can only use 1 of these effects of "Draghig, Malebranche of the Burning Abyss" per turn, and only once that turn
Gen Z and Millennials are in agreement: their obsession with Pokmon may never let up