That's huge
its a list of 40 (currently, anyways) cards that dramatically warp Commander games, allowing players to run away with resources, shift games in ways that many players dislike, block people from play, efficiently search for their strongest cards, or have commanders that tend to take away from more casual games. Heres the list as shared in the announcement article: Itll definitely be interesting to see how the Game Changers list evolves over time
The commanders ranked above represent different paths to victory
With Day of Black Sun, you can destroy cheap, aggressive creatures at a reasonable cost while leaving your larger threats untouched
Plus, it lets you untap target land, so you can even use it as a political tool to help another player out in removing a problematic permanent
Its also a big mana rock, even if you arent going to sacrifice it to return it tapped to frustrate a draw-go player