There are definitely more reasons to shy away from Chain Lightning, but Ill at least put it on the record that including both has always been positive for the gameplay of red decks in my experience
Creature Artifact - Human Samurai Color tag templates(None) Rem Karolus, Stalwart Slayer Flying, haste If a spell would deal damage to you or another permanent you control, prevent that damage
Glaring Fleshraker and It That Heralds the End are nice colorless buffs too, and theyre cheap enough to include in almost every colorless deck, even Eldrazi ones that require lots of expensive permanents
Considering that youre likely trying to beat your opponent down, this can be surprisingly costly
I particularly like Chaos Wand here
While Lashwrithe and Strata Scythe are both good budget options, Blackblade is by far the most consistent and easiest to pull off