The Aftermath is a Standard-legal set, just like March of the Machine before it
The card has become a staple in Hammer Time, but hasnt seen too much play outside of that, other than in some fringe Blue-White Affinity decks and some Thopter Foundry builds
If you find complete, mint-condition boxes or packs, do not open themgrade them sealed for long-term value
If you want to play a longer more mid-to-lategame style deck in Mono Red that interacts more with the table, well, it gets more challenging because it makes Mono Red's inherent weaknesses more glaring: subpar card draw and ramp, subpar answers to creatures, minimal options for enchantment removal, commander protection, and recursion, things that get more pronounced as the game progresses