Dies to Removal

Blood Moon poops on Jund and Zoo, with ancillary value against Affinity. The only decks it's a blank against is Merfolk and Soul Sisters, and straight red burn.

Here's the last version I was brewing on before the Boros bug got me.

[deck]Modern Mono Red[/deck]

Attack with ALL the lands. Or just abuse Koth for bonfires. Or abuse Koth for giant flyers.

Small burn isn't what you want in this deck. I've built many iterations of mono red Blood Moon before, and you need a fat finisher that rewards your mono Mountain land base. Run Koth, profit. You want him every game so 3-4.

Shrine is good, but you really want it early so 4x is right number. I ran 4 in the side and swapped it in for grinder matchups.

You neglected to tell us what type of combo is in your meta. Twin or Storm? Blood Moon barely touches them. Ad Nauseam? Shreds them apart.