Kiln Fiend may have a home here. Love the aggro-burn methodology, +1! Check out mine: Kill it with FIRE!!

the only problem with Kiln Fiend is in this deck Monastery Swiftspear is strictly better being a 1 drop with haste. Otherwise he'd be a great card for me if for no other reason than to bait removal spells.

I've thought about the Swiftspear for my own deck, but it just doesn't hit hard enough, you know? After 2 instants the Swiftspear swings for 3, the fiend for 7. After 3, the ratio is 4:10. I get it, though.

That's understandable because your deck is a slower mid-late game based deck. This one aims to win turn 3-5 so a swiftspear with haste is much more important than getting 1 more power per burn spell.

otherwise I'd tend to agree with you that the fiend hitting harder is much more valuable.

monastery is strictly better because his toughness raises too, kiln fiend need them to have no blockers, swiftspear takes them out. I would suggest getting to at least 18 lands though...

I would disagree, diatryma, on the notion of it being strictly better. More versatile, perhaps, and haste coupled with a lower CMC make for a compelling argument for "generally better." But I find that "strictly" gets thrown around too easily these days. For example, Predator's Gambit is strictly better than Unholy Strength because they cost the same, have the same principle effect, are both enchantments, but the Gambit does just a bit more while being otherwise identicle. Notice that my deck is multiplayer. My mono-red oftentimes sees quicker advancement than bi- or tri-color decks. It usually only takes one of my burn spells to clear a path on someone for my Kiln Fiend . So I, more often than not, hit someone for 10 with just the Fiend. I also run Satyr Firedancer , so I burn my opponent and their creatures simultaneously, making T4 defeats of one opponent a fairly regular thing. So is the swiftspear better? Quite possibly. But strictly better? No, as my brew benefits from the fiend more so than the swiftspear.

sorry, strictly better in a top tier deck designed to win against other good top tier decks. Oops, my bad.

Swiftspears are strictly better for RDW

Fiends are capable of more damage, but not more damage as fast. I can get 6 damage out of a swiftspear by turn 3, and that's in addition to the damage I've done with the burn I used to pump her.

Now, Kiln Fiend can do more damage than that on turn 3, up to 10, but he can also be killed by Shock and doesn't have haste so if he dies before you get to swing, he does nothing.

That's why I like fiends better in Izzet pump decks that can run Izzet Charm and other counterspells to protect it. Other times it's up to preference and your meta