DedWards

Nice use of the Dragon and the Tomb.
Not sure it'd work with your current creature base, but Cloudshift and Retoration Angel can get the Tomb to animate, even when it's not your turn.

I was going through my cards last night and I found a rare enchantment that may or may not work in this deck:
War's Toll

My main idea I got when going through this deck is for you to play 1 mana artifacts like Chromatic Star for "free" thanks to Etherium Sculptor, sac them to Grinding Station to mill 3 and draw a card (hopefully into another one), then repeat as much as you can. Then shuffle them back to repeat the process. So all activations and activities will be "free", leaving mana open for the Elixir of Immortality activation and counter spells.

Cards like Cloudshift and Momentary Blink would be cool with the Allies' enter the battlefield abilities.

Cathars' Crusade would fit in here nicely, it fits with the theme by speeding up the +1/+1 counter gain.

I like the idea, but I have a few suggestions. You may want to include a card that shuffles your graveyard back into your library (Elixir of Immortality, Reminisce, etc) and more artifacts that draw you cards when they go to the graveyard (Chromatic Star, etc).

Phantasmal Image + Sun Titan makes for a almost never dying Titan as long as you keep Sun alive.
Heartless Summoning allows for Titans to be cast 2 turns earlier than normal.

Enduring Ideal I don't see working here for 2 reasons - 1) costs WAY too much mana and 2) the Epic part of the spell will prevent you from playing fogs and kill spells. I suggest taking a look at my Strong Hold on Discipline deck, you may wind a few ideas in it that you could use:
www.mtgvault.com/ViewDeck.aspx?DeckID=229122

The only other thing I can suggest is learn when it is or is not a good idea to give creatures to the opponent. ie use Forbidden Orchid only when absolutely necessary in early game and then as often as possible (even if just to give creatures)when you feel you're in a position to handle the onslaught.

Lightning Bolt and Lightning Helix are better than Incinerate and Searing Spear.

Also you may want to look into adding dual lands. Ideally Sacred Foundry and Arid Mesa, but Rugged Prairie and / or Clifftop Retreat would work well too.

If this runs anything like my Strong Hold on Discipline deck, when to give creatures with Forbidden Orchard is a difficult decision, too early and you'll be overwhelmed, too late and the opponent doesn't get enough creatures for late game wins.

Mercy Killing mite make for a good kill card, it gets around indestructible and gives the opponent more creatures :p

I think you misunderstand how Blowfly Infestation works. You control the enchantment, so you chose what creature gets the -1/-1 counter. Only time the counter gets put on one of your creatures is when the opponent has no creatures left, but even then it is your choice where the counter goes.

Virulent Wound makes for a nice pseudo Scar, so you could effectively run 8 "Scars".

Blowfly Infestation works well with this type of deck.

Arguably the best BW dual lands in Modern:
Godless Shrine and Marsh Flats.

What I use because those 2 are too expensive:
Fetid Heath and Isolated Chapel.

I run a mono black exalted deck in Standard (only because I don't have Isolated Chapel to run WB) and when I do manage to play one of my 2 Nefarox, he rocks the party :p

But seeing that this isn't Standard, I think I'd prefer Divinity's lifelink. That's just my preference, but I do suggest testing it out with each and then decide from there.

I'm not sure I like the Evolving Wilds in here, I'd rather it be not used or replaced with Marsh Flats (that can then be used to fetch Godless Shrine). A cheaper option (I think) would be to use Isolated Chapel and / or Fetid Heath. Also I'm not sure a full set of Cathedral of War is a good idea as it enters tapped :|

Drowned Catacomb and Nephalia Drownyard are lands you want to run in this.
Increasing Confusion is (imo) better than Dreadwaters.
Seeing that you're running black, where's the kill spells for what does come out? And counter spells too?

My confusion lies in how the birds and pilgrims lived long enough. The second the opponent sees Door (if he let it resolve) will send every burn, kill or bounce spell at their disposal to prevent the Door's activation. That is if door survives long enough to untap (there's a lot of artifact hate in standard at the moment).

How do you get 2 of each colour mana? BoP can only produce 1 and does easily. Pilgrim only adds white and suffers the same problem BoP does. Lotus adds 3 of ONE colour. I don't see enough mana fixing to make Door a win condition.

Light of Day + Darkest Hour is actually a combo a friend runs in a casual deck (it's his Light of Day and Darkest Hour that I'd use if I made this). Like I said to psychicvacuum (above), this just a minor modification of my other deck to include the combo.

The BW and BWG token decks that I've faced off against have been some of my toughest match ups (note to self, kill Sorin, Lord of Innistrad asap).

Rotation always shakes things up and more often than not, I'm glad to see certain decks lose their key / good cards. So it's almost impossible to know what to change post rotation, all I can suggest is to watch what your group plays and adapt to that.

This was just a minor modification of my other deck to include the Light of Day + Darkest Hour combo, just for kicks. If I where to make this for serious competition play, I'd probably reconstruct it completely and it'd probably contain Thoughtseizes and the like (Darkness too).