Competitively speaking, the only thing Amber/Emerald has going for it that Ruby/Sapphire doesnt are more plentiful draw cards
Retrieving your good enters creature and ramping is a nice little interaction
This amount of damage kills the blocker
Foil-etched cards are darker but sparkle in the light
While it's a fun and flavorful inclusion, there are better options like Bloodghast or Reassembling Skeleton that offer more utility and resilience
Even when it isnt on the battlefield, the mere threat of Blood Moon forces players to play differently, and its inexorable effects on both the Modern and Legacy metagames are nearly as format-warping as those of perennial powerhouses like Mox Opal, Thoughtseize, Lightning Bolt, Brainstorm, and Deathrite Shaman