For over a year I have been working to make a Wall of Blood deck that was consistent and could win games regularly against another Tier 1/2 modern deck. I tried almost everything, from Fling and Rite of consumption to fling a huge Wall of blood, to using cards like Angels grace, Near death experience, and Death's shadow to take advantage of Wall of blood's ability to lower your life to any value you want. I even tried to throw wall of blood in a Jund shell--but to no avail. When the decks won, the victories were a sight to see and sometimes hilarious. But i noticed that either my deck was too vulnerable to disruption and inconsistent most of the time, or throwing Wall of blood into a preexisting deck just made the deck a weaker version of itself--winning without utilizing Wall of blood.
The reason Wall of blood/Fling is an inherently weak combo is this:
1. You must have higher life points than your opponent to combo off with a Fling. Usually you get the combo pieces late game and by that time you're usually almost dead.
2. Wall of blood is easily removed from the field with creature removal
3. Inconsistency/vulnerability. Fling did not gain life after using it and you would lose 2 combo pieces if you did not kill the opponent with one shot. This required you to spend several more turns looking for more combo pieces with a low life total. Fling's Sorcery variants that do gain life (Rite of consumption and Essence harvest) had the same problem but with the added hindrance of having Sorcery speed, so they could easily be countered or responded to with a removal spell.
I eventually reasoned that if i wanted to utilize Wall of blood effectively, i would need to find a way to have access to its ability while its off the field, along with any other cards that combo with it, to avoid counters, removal, and discard. This brought graveyard decks to mind. Thankfully, I knew about Necrotic Ooze for some time and its ability to function like a Swiss army knife. Once I found out there was a combo to mill my own deck with him (while gaining life doing so), as well as a creature that flings itself with an activated effect that costs only 1 colorless mana, I knew I found what I was looking for.
The combo used to mill this deck seems to have been destined for Wall of blood.
The combo works like this: If you have Necrotic ooze on the field, Civilized scholar in the graveyard, and Golgari brownscale in your hand or graveyard, you can mill your own deck. You tap Necrotic ooze and use Civilized scholar's effect: draw 1 card, then discard 1 card. If you discard a creature card, untap Scholar and transform it. Since Necrotic ooze can't transform, he simply untaps and is able to use the ability again. If Golgari brownscale is in your hand, you discard him and use ability again. If both Brownscale and Scholar is in your graveyard, You replace the draw aspect of Scholar's effect with Brownscales dredge 2 effect; this is where this combo synergizes with Wall of blood. When Brownscale goes from your graveyard to your hand, you gain 2 life!!! So you are gaining 1 life per milled card. Tap Ooze, dredge 2 cards, put Brownscale to hand, gain 2 life, then discard Brownscale to untap Ooze. Usually you can mill around 30 cards which gives you more than enough life to fling an extra large Ooze at your opponent. You mill your deck until you have Wall of blood, Skarrgan skybreaker, and enough life to comfortable combo off. Furthermore, you can use Thornling's trample ability to attack with Ooze before you sacrifice it, in case the opponent would respond to your Skarrgan ability with a game winning spell.
This solves the 2 major problems with Wall of blood/Fling combo:
1. You no longer need more life than your opponent to combo off; You can win the game even with 1 life left.
2. The Fling effect will not be countered 99% of the time, unless opponent is running disallow (highly unlikely)
This deck still has a hard time with creature removal, but if you are fortunate to have a Thornling and a Civilized scholar in your graveyard when you land a necrotic ooze on the field, you can either respond to the removal spell with haste ability and combo off or activate the indestructible ability if don't have the complete combo yet. This requires 1 green mana up.
Control decks can give this deck a hard time, so there is 4 Cavern of souls in the deck to give it a fighting chance. You can bluff the opponent by attempting to cast your combo pieces in order to lure out counterspells while sending said pieces to the graveyard where they are needed. You can also wait to cast the Necrotic ooze late game when the opponent taps out, ideally with Thornling in the graveyard for haste.
Magic Rulings that you may need to reference:
Rule 701.26c If a spell or ability instructs a player to transform a permanent that isn’t represented by a double-faced card, nothing happens.
(This means Necrotic Ooze cannot transform and nothing happens after he untaps with Scholar's ability.)
Rule 609.3 If an effect attempts to do something impossible, it does only as much as possible.
(This means that Scholar's effect resolves as completely as possible, omitting any impossible actions, such as transforming Necrotic Ooze)
Rule 201.4b If an ability of an object refers to that object by name, and an object with a different name gains that ability, each instance of the first name in the gained ability that refers to the first object by name should be treated as the second name.
(This means that when Necrotic Ooze uses Skargaan's or Scholar's ability, any instance of their names in the effect should be treated as if it was referring to Necrotic Ooze.)
How to Play This Deck:
1. Wall of blood is a great wall for anything without flying or protection from black. However, be reluctant to put Wall of blood on the field, because if opponent refuses to kill it or if opponent exiles it, you will lose the game unless you have another Wall of blood in the deck.
2. Never sideboard out more than two Sylvan Caryatid in games 2 and 3. If you have one tapped on the field and zero mana, you wont be able to use Skybreaker's ability in response to a game ending play. When you finish milling your deck, there will be no Sylvan Caryatid in your graveyard for Necrotic Ooze to be able to tap itself for mana if you need it to cast Skybreaker ability.
Example: I Lost to Blue Tron when I should have won. I had 6 mana on my turn. Used one G mana for Fauna Shaman ability searching Brownscale. Used 4 mana to cast Necrotic Ooze. Scholar and Thornling were in graveyard and I had one G mana left. Opponent activates his Oblivion Stone. I respond with activating Thornling's haste ability. I then had zero mana and was not able to complete the play since I didn't have the last mana to use Skybreaker's fling ability. If I had Sylvan Caryatid in graveyard, I could have pumped up my Ooze with Wall of blood, tap Necrotic Ooze for one mana any color, then use that mana to fling my pumped Ooze at the opponent and win.
3. Remember Necrotic Ooze can tap itself for mana if there is a Sylvan Caryatid in graveyard.
4. Pili Pala's ability can win games when it responds to anything that responds to Necrotic Ooze's activated ability. Pila Pala may also give you a second chance to find Brownscale when using scholars ability, do a double Fauna Shaman search, or activate an ability after a Fauna Shaman search.
Sideboarding
1. Fauna shaman fetches Trinket mage for Pithing needle. Cavern of souls and Sylvan Caryatid can produce blue mana.
2. Gnaw to the bone is for burn. It is effective if you are fortunate enough to have milled it with a few creatures using 1-2 Grisly salvages/Communes before turn 4.
3. Sturdy hatchling is there to replace Thornling's indestructible abiltiy with a shroud ability, specifically for Path to exile. Side board probably needs 1-2 more of these.
4. Caustic caterpillar is there for trouble enchantments or artifacts. Ancient grudge is probably a better option if you have a Sylvan Caryatid in your opening hand or if its milled with Grislys/Communes.
5. Damnation is for aggro decks or any deck that dominates the board with creatures. Needs to be topdecked with 4 mana sources within the first 11 cards to be effective. Otherwise, you will probably just mill a dead card.
6. Spellskite is there because it is Spellskite. Fetch it with fauna Shaman