removing cards from the graveyard tends to correlate to grindy games that benefit from a creature you can chuck into play that slowly accrues advantage over a long game, especially if you throw in some cards that care about zombies or tokens
Before we talk about why certain Reserved List cards are increasing in price now, lets talk about why some Reserved List cards lost value over the past couple of years
Their card text often revolves around "Whenever a Samurai or Warrior you control attacks alone" as the source of its mechanical payoff
It is five colors so you can play any Dragon in the format you want
Toxic Deluge is one of the best black board wipes in the format, scaling its kill power to slip past indestructible creatures, and Skullclamp remains the gold standard of cheap card draw
Once you move into the higher brackets, Optimized and cEDH, anything goes