Murderous Rider // Swift End Perhaps you've noticed a trend by now - Removal spells attached to creatures are good
Blues combat tricks focus on making creatures bigger, like Serpentine Ambush and Wings of Velis Vel
As an enchantment it does one thing: doubles all damage sources you control of the chosen creature type deal
At first glance it looks like you would only want to play this card in a Zombie deck, but its much better and more versatile than that
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