Muktol

http://www.mtgvault.com/muktol/decks/monou-self-mill/
Same approach but I utilize some tutors here to get Leveler into my hand (or on the table), and the Maniac is searched via 'transmute' effects. Also my version is modern legal. For Legacy I would use "Tinker" and "Counterspell"

Greetings
Muktol

"Dark Ritual" is not modern legal, if that was the question.

Greetings
Muktol

OK, so we can already remove Doorkeeper, Chronic Flooding, Tome Scour, as those cards belong to milldecks.
Next question is, how do you want to beat your opponent to zero, fast with many small creatures or control his play and beat him with slower but stronger creatures. As this site allows many decks, you ca also built a second deck and try a different strategy.
Before you buy a card, try to print it as a proxy and test it.

Well, if you want to, we can try to work it out together.
Are these the cards available to you, or do you have other cards to (and perhaps are willing to buy some)
First we need to define a rough strategy of the deck: beat your opponent to zero life, reduce his library to zero or alternative measures (a special card that says 'when XYZ happens, you win the game')

Let's see which cards could stay, and which should be removed.
"Balustrade Spy"...Remove, he belongs more into a mill-deck
"Blood Seeker"...Stay (or put into your sideboard), if your opponent just plays some few creatures, the 1 point of lifeloss won’t hurt him.
"Child of Night"...Stay, until you find something that suits you better, as she lacks avoidance.
"Chosen of Markov"...Remove, cc3 for a 4/4 without any avoidance is just bad.
"Duskmantle Prowler"...Exalted is good if you just attack with one creature, otherwise remove.
"Falkenrath Noble"...Combined with a mass-removal he can be used as a finisher, otherwise remove. "Sengir Vampire"...Can be kept, expensive but good
"Shadow Alley Denizen"...Keep, as you play enough black creatures to use this effect.
"Vampire Nocturnus"...Keep, no more words needed I think ;)
Guildscorn Ward...put into your sideboard, as you don’t encounter multicolor-creatures every day.
Path of Bravery...Remove, your opponent always will have something so say about your lifepoints. Also cc3 for an unsure +1/+1 is not that good.
Spirit Mantle...Keep, cc2, +1/+1 and unblockable (creatures cant target him) is always a good thing
Crypt Incursion...Sideboard, useable when your opponent plays many spells that depend on his graveyard.
Dark Ritual...Depends on what will get out of this deck. If you feel that you need some mana-acceleration it’s OK, otherwise remove.
Demystify...Sideboard, useable when your opponent plays many (or annoying) enchantments.
Grisly Spectacle...Remove, belongs into a milldeck, and there are cheaper removal-spells.
Rescue from the Underworld...I would remove it, as it is rather expensive to play.
Shielded Passage...can be used to safe a creature from lethal damage, can be used but can also be removed.
Smite...Remove, you don’t want to block, you want to attack ;)
Whip of Erebos...Keep
Sorin, Lord of Innistrad...Keep
Blood Tithe...Remove, cc4 for 3 life is not good
Debt to the Deathless...very expensive and intensive in its mana costs (double black AND white), I would remove it
Eradicate...Keep, very useful to stop your opponent from playing annoying creatures.
March of the Returned...Remove, creatures die and that’s the point why you need 4 of them.
Rise from the Grave...can be used to steal an enemy creature from a graveyard, but is very expensive.
Solemn Offering...Remove.
Undercity Plague...sideboard.

And you should try to raise the number of lands to 20, or even 22

Greetings
Muktol

I mean no offense, but please, take a look at http://www.mtgvault.com/muktol/decks/how-to-build-a-deck/
At the moment it looks more like a commander deck than a regular deck.

Greetings
Muktol

Thank you for all your suggestions.
Those are all very plausible, but most of them are not modern legal, and I want to stay within this legality (I hope I did the right deck-tag).

Boom // Bust (and I normally don't want to play the bust part, you're right) enables me to remove a land in turn 2, a option that no other (modern) spell has. I think it is very important to disrupt my opponents play as early as possible and still have the option to play or wait wait until next turn (e.g. not enough mana next turn when played, "Darksteel Citadell" just drawn) .

I will reduce "Detrivore" to a 1-drop and increase the number of "Magnivore" instead.

cc1, 3 damage, suspend vs cc1, 2 damage, playable when you need it...will depend on my opponent's deck but I will give it a try.

I would remove "Adaptive Automaton" as you allready have a huge ammount of lords in this deck. "Æther Vial" could be a good replacement for this.
Also you should maybe add some lands ;)

Some (few) suggestions from my own monoU merfolk deck (http://www.mtgvault.com/muktol/decks/monou-tribal-merfolk/)
Silvergill Adept (2/1, carddraw)
Savor the Moment (extra turn, skip untap), Merrow Commerce (Untap your merefolk at each end of turn), Aquitect's Will (Target land becoms an island, draw a card if you control a merfolk)

Greetings
Muktol

Some suggestions, based on my monoR burn deck (http://www.mtgvault.com/muktol/decks/monor-burn/)
Magma Jet ({1}{R}; scry 2; 2 damage on player (or creature), library manipulation), Needle Drop ({R}; 1 damage to a player that was dealt damage this turn; draw a card), Shard Volley ({R}, sacrifice a land; 3 damage to player (or creature)), Rift Bolt ({R}, suspend 1, 3 damage to player (or creature), Vexing Devil ({R}, 4/4, if opponen wishes you sacrifice him as he enters the battlefield and opponent gets 4 damage)

Greetings
Muktol

I mean no offense, and I read that this deck was built out of cards you have at home, but read
http://www.mtgvault.com/muktol/decks/how-to-build-a-deck/
Basicaly use some fewer cards but those more often, think of a strategy and stick with it (e.g. "Balustrade Spy" belongs more into a milldeck as you have nothing that helps you take advantage of some cards in your opponents graveyard)

You also should take a look at the decks legality, if you want to play it in modern or vintage/legacy. This choice has a huge influence on the available cards.
After you have decided this, we can start working on the deck :)

Again, I menat no offense.
Greetings
Muktol
(Sorry for my bad english, I am no native speaker)

I would reduce the number of lands to 20, and use more standard lands, as they don't enter the battlefield tapped.

Some suggestions, based on my own monoG infect deck (http://www.mtgvault.com/muktol/decks/monog-infect/)
Signal Pest ({1}; 0/1; battlecry; can only be blocked by flying or reach)
Bonesplitter ({1}; {1} to equip; equiped creature gets +2/+0)
Evolution Charm ({1}{G}; very flexible, search a land, return a creature from grave, give a creature flying), Groundswell ({G}; +2/+2; with landfall +4/+4), Mutagenic Growth ({G} or 2 life; +2/+2), Vines of Vastwood ({G}, Kicker {G}; Hexproof, if kicked +4/+4)

I hope I was able to give you some ideas
Greetings
Muktol

Looking good
You could try to reduce the number of lands to 20 or even 18 as you play many low-cost spells.
I would try to raise the number of "Mogg War Marshal" and "Quest for the Goblin Lord" to 4, as these are very good spells. A 3rd Krenko could be an idea, as he normaly gets shot away faster than you can say 'Bolt'

Some suggestions, based on my own goblin deck (http://www.mtgvault.com/muktol/decks/monor-tribal-goblins/)
Furystoke Giant (Another finisher, advantage is, that your creatures don't have to attack to give your opponent the rest), Goblin Wardriver (Battlecry), Spikeshot Elder (If you're having to much mana and don't know how to use. Very good when buffed), Warren Instigator (Doublestrike, fastens your play and people fear him)
Teetering Peaks (Land, when it enters the battlefield (tapped), creatures you control get +2/+0)
Infiltration Lens (carddraw), Æther Vial (Speeds your play)

Greetings (and *like*)
Muktol

I'm really missing "Ethereal Armor" and "Hyena Umbra" here. I would take at last "Pazifism" out, perhaps "Lifelinkt" too.

Greetings
Muktol

True enough, I forgot that you can play up to 4 "Bushi Tenderfoot", the don't count as legendary. Many Kamigawa flip-cards are both sides legendary, so perhaps the mistake came from there. ;)

I really miss "Rancor", "Ethereal Armor" and "Daybreak Coronet" here.
I would also add some more duallands to stable your manabase.
"Bushi Tenderfoot" could be reduced to 3, as he will become legendary when flipped.

Greetings
Muktol

"Guul Draz Assassin" could be an alternative to "Falkenrath Exterminator"
I play rather aggresive decks, and even ramp decks should utilize something that protects them in earlygames.

If you want you can take a look a my own B/R vampire list, I normaly only link those if I am able to make some suggestions, based on one of my decks (http://www.mtgvault.com/muktol/decks/br-tribal-vampire/)

Greetings
Muktol

I would sideboard "Viridian Corrupter" as you want to be fast and aggresive and thus don't need a artifact removal all the time. Use the free slots to fill up "Ichorclaw Myr" as nobody normaly wants to block a 1/1 that gets a 3/3. Another option could be "Signal Pest", see suggestions. Also I would think of removing "Primal Bellow" as, in the starting phase, it is weaker than most similar spells.

Suggestions, based on my own infect deck (http://www.mtgvault.com/muktol/decks/monog-infect/)
Signal Pest ({1}; 0/1; battlecry; can only be blocked by flying or reach)
Rancor ({G}; +2/+1, trample, if it would go into your graveyard, take it onto your hand instead), Wild Defiance
Evolution Charm ({1}{G}, very flexible. search a land or return a creature from graveyard or creature gains flying), Vines of Vastwood ({G}; target creature gains hexproof; {G} Kicker, if kicked, target creature gets +4/+4), Might of Old Krosa ({G}, +2/+2 if not played in your mainphase, +4/+4 if played in your mainphase)

I hope I was able to give you some ideas
Greetings
Muktol

I would change some things here:
Raise "Elvish Archdruid" to 4 and decrease Elvish Champion to 3. You will need the mana and as you don't have anything that can turn an opponent's land into a forest, so forstwalk will be very situative.
Decrease "Timberwatch Elf" to 3 or even 2. With trample it should be enough to buff a single infect creature and let it attack.
Remove "Joraga Treespeaker", you should have enough mana from "Elvish Archdruid"
Change from "Elvish Herder" to "Rancor". Rancor is harder to remove and even buffs your creature with +2/+1 for only {G}
Add 2 "Bramblewood Paragon". This card buffs all your elf-warriors, gives them trample and, with only cc2, comes rather early.
"Viridian Corrupter" could be put into your sideboard. Yes, you loose a infect creature, but you have enough elves to compensate this.

Some suggestions:
Wirewood Herald (Tutor for elfes), Sylvan Messenger (Carddaw), Elvish Visionary (Carddaw), Ezuri, Renegade Leader (Built in overrun and regenerate for any other elf)

Greetings
Muktol

Some suggestions
Nephalia Drownyard (Land, allows you to mill, even if you don't have any handcards), Jace's Phantasm (At last a sideboardoption against decks that manage to get some creatures out), Pilfered Plans (I think that "Visions of Beyond" won't be enough as carddaw)

Greetings
Muktol

I would rather use "Koth of the Hammer" than "Chandra Nalaar"

Furthermore some things I would change:
Remove "Akki Rockspeaker"...you have better creatures in your deck to fill the free slots.
Remove "Flamekin Harbinger"...I would rather use some draw-spells
Remove "Legion Loyalist"...Most of your burn-elementals allready have trample, and as they nevertheless die EOT, they don't need first strike. Perhaps a sideboard option if you have to play against first strike decks rather often.
Remove "Ogre Sentry"...You want to stay aggresive and thus don't need defenders
Remove "Memnite"...I don't see how it should fit into your plan.
Sideboard "Stigma Lasher"...I hope you don't encounter a lifegain-deck every match ;)
Sideboard "Smelt"...Use when going after artifacts, but again. not every deck utilizes them.
Raise the number of "Ball Lightning" to 4
Raise the number of "Goblin Wardriver" to 3
Raise the number of "Signal Pest" to 4
Raise the number of "Spark Elemental" to 4

Suggestions, based on two of my decks (http://www.mtgvault.com/muktol/decks/monor-tribal-elemental/); (http://www.mtgvault.com/muktol/decks/monor-burn/)
Hellspark Elemental (Elemental with unearth), Nova Chaser (strong element, can be used to re-use your burn-elements like "Spark Elemental"), War Elemental (Strong element), Needle Drop (Carddraw), Searing Blaze (Creature removal), Magma Jet (Card manipulation)

I hope I was able to give you some ideas
Greetings
Muktol