Have you considered using Utter-End? It's also known as the Poor-man's Downfall. But it handles Planeswalkers, opposing dragon threat recursion from Haven of the Spirit Dragon (except the hexproof guys) and well, literally everything. I suppose it doesn't handle Nissa Worldwaker's Land Creatures. It is a solid card though. They are reasonably cheap as well.

The 4 Mana cost may be a bit unappealing for a removal card. I can understand that. One way to off-set the drawback of such a large mana investment for a 1-1 trade, is to rely a bit more on Delve. This will allow you to cast more things in the earlier game while being slightly less mana hungry.

Some of your cards do not support Delve very well. Things such as your white, enchantment based removal cards. That's fine though. It isn't necessary to force the deck run things that promote Delve. Supporting it, however, will increase speed and efficiency for doing so. I have seen decks run a Tasigur, 3 Murderous Cut, 4 Dig through time and 2 Treasure Cruise, all in a Blue/Black control deck. You could handle a bit more delve.

I feel Murderous Cut is a better removal spell then some of the options you have main boarded. It surprises me see the enchantment based removal in your deck. This is something you typically see in the U/W or U/W/R control builds due to Red's lack of ability to handle large creatures. White this format got a bit shafted on efficient, low Mana cost removal. Running Black fixes that. So there isn't much need to run such a heavy white spread, or use White's removal over Black's. However, if this suits your local Meta-game, it is perfectly understandable.

I think I see why you are having such a tough time with aggro/token based decks. You are attempting to play a Dragon/Control deck, right? However, most of the removal is 1-1 trades. While this is good in theory and efficient in the late game, it does little against some decks. Some decks can deploy multiple threats per turn at equal or lower Mana investment. RDW, Token variants, Black Aggro etc must be a nightmare for you.

I propose running higher utility removal, more cards with the option to trade 2-1 (especially in the early game) and promoting Delve as a higher priority.

As you mentioned, you lack Hero's Downfall. While you can substitute creature removal with other spells, you are at a loss for instant speed Planes-walker removal. This means you have to wait until you can Banishing Light. The same problem is true for facing Ascendency combo builds, or anything that uses artifacts or enchantments. Remember the recap you gave on Match 4, where you lost to Back to Nature? That is because Enchantment based removal is weak to these types of effects (as well as Ugin and Perilous Vault, which are everywhere).

Crux of Fate is AMAZING. I don't think anyone will deny that. However, it is also 5 Mana. The reason this is inconvenient is due to it not costing 4 Mana. Most Aggro decks intend to win by turn 4...

To make it to turn 5, you may need additional support. Cards like Bile Blight can really make a difference. It can sponge damage when you are being attacked, make a nice combat trick, be 1-1 removal spell, or mop up a bunch of tokens at instant speed. It is pretty amazing.

My personal favorite, however, is Drown in Sorrow. I love this card. Not only can it white the board of many aggressive creatures in early turns, it doesn't target. White counter-magic cannot protect their creatures (God's Willing etc). Killing creatures with "protection" and "indestructible" is nice. Boosting toughness usually means they trade a pump spell on your turn for Drown in Sorrow, so it won't increase damage you take on the following turn. Finally, it lets you Scry.

I also noticed the lack of hand control. White I understand that Thought-seize is disgustingly over-priced, there are some good alternatives. Duress, Despise, and Mind Rot. They are all proactive plays (which is nice in mirror match ups) and manually feed Delve without waiting to react to an opponent's actions. Duress and Despise are also nice due to the low Mana investment for playing them, leaving counter/removal Mana open. Individually, they may not do much in bad matchups (Duress vs aggro/monsters, Despise vs control), they are REALLY good against the match ups they help in. I personally prefer Duress because you have field sweepers for creatures that hit the board. Pre-Emptively hitting removal/Walker/Counter magic is really good.

I'll post a mock-up build with cards I've suggested (as well as some other reasonable/affordable cards) and with what you already have showing in your list.

Lands (25)

x4 Temple of Deceit

x2 Dismal Backwater

x2 Tranquil Cove

x4 Evolving Wilds

x2 Caves of Kolios

x4 Island

x4 Swamp

x1 Plains

x1 Haven of the Spirit Dragon

x1 Crucible of the Spirit Dragon

Instant (21)

x4 Anticipate

x2 Dig Through Time

x4 Dissolve

x3 Silumgar's Scorn

x1 Disdainful Stroke

x2 Ultimate Price

x1 Bile Blight

x2 Foul-Tongue Invocation

x2 Utter End

x2 Murderous Cut

Sorcery (7)

x2 Treasure Cruise

x2 Crux of Fate

x2 Drown in Sorrow

x1 Duress

Planeswalker (1)

x1 Ashiok, Nightmare Weaver

Creature (4)

x2 Belltoll Dragon

x2 Silumgar, the Drifting Death

Sideboard (?)

Utter End

Radiant Purge

Liliana Vess

Negate

Ultimate Price

Virulent Plague

Resolute Archangel

Pristine Skywise

Ojutai's Command

Monastery Siege

Duress

Despise

Prerogative

Swansong

• other stuff?

The ideas behind the edits are to give a more rounded match up against aggressive decks, while trying to maintain the deck's main concept.

Lands: The edits are done to further support color fixing in the early game. B/U are heavy in this build, so there is more Mana sources for those colors. The Terramorphics count as CIP tapped lands, but can search any color. It also supports Delve. The double B/U should be easier to cast. The Crucible is an interesting choice. I don't know if your deck's low dragon count and lack of Ugin would make a 2nd Haven a better choice or not. It was left at 1-1 Crucible/Haven. From personal preference, I like Haven at 2, and more targets to get with it.

Instants: Small adjustment to counter magic. Disdainful Stroke does stink against aggro decks. However, 2 drop counters are really nice. While Scorn is amazing, you may not always have a Dragon handy. Disdainful Stroke is the most efficient way to handle opponent's big draw spells (Ingenuity, Cruise, Dig) as well as Green fatties, Planes walkers (-Ashiok) and all Dragons. The removal package has been flexed a bit, being less redundant, but more flexible. Additional copies of your favorite removal spells can always be sided in if you enjoy having 4 of's (like Ultimate price) vs certain match ups. Prerogative was dropped for Treasure Cruise for efficiency. Prerogative is nice, drawing 4 cards, nigh uncounterable and instant speed. However, Utter Ends are slightly mana hungry, and this suits the curve well. The choice is yours to make though.

Sorcery: I feel Drowns/Cruises are a must in decks like these. Well, Cruise can always be Dig, depending on budget/preference. Drowns keep the early game clear and keep you alive to reach your late game state. Only a splash of hand control here, though with some playtesting you may find additional room. I couldn't think what else to drop for a second option. Perhaps a Scorn? But it's fine at 1.

Walker: I'm torn between Lily and Ashiok in the mainboard. I almost prefer to run both, or only Ashiok. Not that Lily isn't amazing. Again, it simply reflects the curve of the deck. Most B/U or Esper control variants seek to go big or go home. They top out at Ugins/Silumgars for hefty mana consumption and late game power. But with your budget not allowing you to play the power house cards at the top of the curve, there is no reason your deck should play as long of a game as theirs. There isn't anything in the list that rewards you for a game running that long.

Creatures: I think they are fine "as is." I do like Pristine Skywise though. It is an interesting card and falls into your color scheme. It's superior size at the same Mana cost as your other win conditions convinced me to promote this card. Without having Ojutai, you can't put someone on a 4 turn clock. With Silumgar and Belltoll, they are on a 7 turn clock. This is twice the time Pristine takes to end the game. Also, smaller hitting creatures for win conditions means that your opponent's small/incremental life gain has a greater influence on the game.

While Prestine is no Ojutai, and lacks hexproof, it's not beyond protecting itself. it is a 6/4 flyer at 6 Mana. It still hits like a truck. It gain's it's "hexproof" off of it's soft Prowess trigger. This also makes opponents reluctant to attack since they know any draw/removal spell can turn Pristine into a blocker again by untapping it. 6/4 Flying blocker with protection from the color of your choice... For a budget card, I'd say he sounds pretty good to me. Give it some thought.

Sideboard: Eh, play around with it after you get the main deck functioning where you would like it to be. Personally, I would grind out as much hand control/removal into the sideboard as I could to deal with combo/burn/control matchups, and put the heavy creature removal into the mainboard to deal with aggressive/mid range decks.

Wow, I wish these suggestions came sooner! The 2:2:2:2 Bile Blight/Ultimate Price/Drown in Sorrow/Murderous Cut really balance out, and don't break the budget with relatively expensive playsets (Blight and Sorrow).

Also, looking back, how the hell did I overlook Pristine Skywise? Hindsight truly is 20/20, and yes, the long clock from the current build is awful. I do have 3 Dig Through Time, so in this build I would probably run all of those and no Treasure Cruises at all.

The only points I would disagree on are Ashiok/Liliana. Liliana won me games. Tutoring for whatever I need in a pinch is great. Game-changing, even. I wouldn't want to lose that utility in the mainboard.

I will also point out that waiting a turn for Banishing Light over Utter End isn't as disruptive as you might think. The only downside, and sadly a weakness of white removal, is that it can be removed. A Jeskai Ascendancy or some kind of planeswalker aren't cards that need to be dealt with immediately after their resolution. Planeswalkers get at least one activated ability to go off before I can interact with them anyway, and tapping out (or nearly tapping out) to remove something was crippling when I ran it. Being relatively low-cost, coupled with running other white removal, made Banishing Light very consistent while sadly reducing the decks ability to respond to a hoard of creatures (black is the only reliable way to respond such a strategy).

Due to the ~drastic~ meta change in Game Day 2, which revolved around creatures/'walkers that trade nicely 1-1, the deck performed much better. Sadly, Magic will become somewhat inaccessible to me in the coming months, so this deck will likely be shelved.