Since you've added green, you should try to fit in a few of one of my favourite cards: Wild Defiance !

I would suggest running some kind of hexproof or protection for your creature.
Another weakness would be that you pump up a huge Kiln Fiend and the opponent casts Geth's Verdict

Apostle's Blessing is an absolute must for a kiln fiend deck. It's 1 colorless mana that can be used as a Distortion Strike to get past blockers or more importantly as a pseudo-counter against removal. Honestly, everything in a normal pauper fiend deck should probably be in there, except the lands.

I would add:

4x Delver of Secrets  ^Flip - I know he doesn't get buffed like the other guys, but he WILL win you games. T2 flipped delver attacking w/ Mutagenic Growth & Assault Strobe is 10 damage in the air.

2-4x Lightning Bolt - One of the best spells in Modern. Its just as strong in this deck as any other. 3 to the face plus pump your dudes OR take out a troublesome creature.

4x Apostle's Blessing

2x Mizzium Skin You need more protection. Modern is chuck full or removal.

1x Artful Dodge - Better than Distortion Strike imo. You can cast it twice, pumping guys twice in the same turn or whenever you need it.

2-4x Serum Visions - Ponder & Preordain are a big part of the pauper version, which makes me think this might not be so awesome in modern :( If you do put in Delver, I would for sure put in 4 of serum.

I would take out(In this order):

3x Distortion Strike

4x Brute Force

4x Titan's Strength

3x Wee Dragonauts (if you put in Delver)

Landwise, Sulfur Falls would be a good fit. You would need to take out the City of Brass for them.

Other possiblities you could play with:

Izzet Charm - Lots of options, none of them pump your guy or damage opponent though, also 2 cmc is bad.

Quicken - Cantrips and lets you cast Assault Strobe as an instant.

Stamina you need some sort of removal spells on your sideboard. AT my LGS, several Modern players ask the same question as this deck can fire off on turn 4, the play at my LGS is usually a turn 6 or 7 win condition.

Nice deck, i made my own How to annoy your friends(budget)I recommend Apostle's Blessing and Faithless Looting

no Charmbreaker Devils ?

Jdvanliew I would play Epic Experiment at kitchen table Magic as it seems like a go off combo that would be really fun against friends, but for FNM: Modern I like the consistency of drawing and not having 3 of my 11 creatures go to the graveyard. As this deck has no graveyard extraction. Thanks for the recommendation, I have a play set of Epic Experiment so I will test this out.

shadow63 I had originally considered Charmbreaker Devils , but in test play with my friends and at my LGS found it to be slight to slow for Modern play. I ran 2 but decided to pull them. Charmbreaker Devils is a really good card though and would probably include it in a variant of this deck.

Decent build. My friend SolelyUbiquitous and I have been working on our own version, The Fiery Kiln. Some of the best spells in it are Flamekin Harbinger to help with the Kiln Fiend on turn 2 and Apostle's Blessing to either protect your fiend or push damage through. Manamorphose is also really good for your Phyrexian mana and "storm" count.

Monastery Swiftspear as a fast hitter? Guttersnipe might be more reliable than Wee Dragonauts

Crimson Wisps combos well with Blistercoil Weird .

Manamorphose works like Gitaxian Probe except you don't lose life.

Dang +1 from me this deck is fun to play an still seems good and consistent if you should change anything I would change wee dragonauts for Monastery Swiftspear it gives you a super easy turn 3 win since you can still target the kiln and swiftspear gets boosted just something to think about

I would put in 2 Guttersnipe and 2 Armed / Dangerous , Guttersnipe means you don't have to swing, and also makes you a terror in group games, and Armed is another instance of double strike. Goblin Electromancer also never hurts this sort of thing. Other good options include Hidden Strings which is honestly one of the more insidious sorceries in the game. It can be used to tap blockers, or untap lands, making itself virtually free, and giving you extra mana on a hit. Also, with Electromancer, it actually nets you +1 mana. For other ideas, feel free to check out my UR Proto-GutterStorm which basically has the same game plan.

The problem I've generallally had with Hidden Strings is that it doesn't really... do anything. It's sorcery speed, which is a bummer, and the "tap a blocker" thing matters for nothing when you're running Artful Dodge and Distortion Strike both as 4x in the main board. It's just too slow. This type of deck needs to win by turn 3 or 4, or it flounders and dies. I didnt even use it when the Nivix Cyclops + Armed was in standard (oh man that was a fun standard deck)

I suppose that makes sense. Primarily, I like it because it often serves as just a free sorcery. Under most circumstances when I use it, it is basically "0, cast this sorcery." Also, I find my own deck using Guttersnipe more, so when it lets me untap more lands after swinging, I find that it can easily clinch a game.

I've created a budget version of this deck :D

Not much fun to play against

Replace Wee Dragonauts with Flamekin Harbinger so you can dig for a Kiln Fiend and replace Dispel with Mizzium Skin because it serves the same purpose but can also defend against non-instant spells.

I just want to point out that you have 17 cards in sideboard. just a heads up, that could cost you something at some point.

I have a same kind of deck. But i am also running Delver of Secrets  ^Flip.

I suggest dropping either Artful Dodge or Distortion Strike. I think one of both must be enough. And then i suggest adding 2 Vapor Snag and 1 or 2 Mana Leak. This way you will still be able to push through your opponents defences. And you are more capable to deal with you opponent his threats. I suggest dropping Distortion Strike because you can still use it when it comes in to the graveyard.

Also I dont think you need the back up Nivix Cyclops is needed, defenitely nof a 4-off. And a backup-backup is defenitely not needed. I would drop Wee Dragonauts and drop 2 or 4 Nivix Cyclops and replace them for 4 Lightning Bolt. Lightning Bolt is just too good. This way you can kill threats and clearing the field or keep poking your opponent even more. Also Monastery Swiftspear is worth playing 4 times.

I would also drop Mizzium Skin because al lot of times it will only safe you from threats that target only one creature. And you wont be protected from boardwhipes as Wrath of God. With Dispel, Spell Pierce or Mana Leak for example you are able to stop any of those kind of threats.

Also if you add counters like these you should be able to be deal with more kind of situations, such as kill cards, other counters, board wipes and sometimes even creatures.