(13) W = 4+2+4+4 = 14
(20) U = 4+7+1+4+4 = 20

/r/spikes:
The mana base is really strong - the key requirements that it meets are UU on T2 (20 U sources), W on T3 (14 W sources) and WW on T5 which it passes based on Frank Karsten's CFB lands article.  With only 8 tap lands, it will also hit those conditions untapped very frequently, which is key on the draw to access/represent Silumgar's Scorn, Anticipate and post-board 2-mana removal.  Haven of the Spirit Dragon is a nice way to re-buy a dragon in the late game and you're still gaining so much life from Tranquil Cove and Radiant Fountain.

Silumgar's Scorn has proven to be very powerful both in terms of its actual playability and representing UU with your mana base.  With 7 dragons, it is almost always straight-up Counterspell.  I've had some interesting mid-game interactions where I can respond to a spell with Dig Through Time to find a dragon, Scorn or both to hard counter my opponent and follow up with a threat to really change the game's tempo in your favour.

Narset Transcendent is a strong mid-to-late game draw engine.  I've found most opponents ignore her because of the absurd starting loyalty and go for broke on my life total.  She works best when you are in a board stall rather than when you are behind.  I would only tap out to cast her when I have a Banishing Light in hand (and not playing vs Stormbreath Dragon/Nissa Worldwaker decks).  Otherwise she would come out on T6/T7 at the earliest so I can still represent (and likely have) counter magic.

Dragonlord Ojutai is incredibly imposing - with 5 power, evasion and virtual hexproof he can halt most beatdowns, buying you even more time.  Running 4 seems initially silly but the redundancy helps by trading with an opponents threat when behind or just hitting, then recasting to give him hexproof "again."  He will often eat your opponents rotting removal spells in game 1 with your first attack.  Otherwise, Ojutai is a fast clock and you've basically won with the free Anticipates if your opponent doesn't remove him after the first hit.

Icefall Regent is filler that buys time and consumes a lot of your opponents resources to remove.  Late game he's strong enough to lock down your opponent's remaining creature and go in for the beat down.  Like Ojutai, he does enable your opponent's removal but it usually comes at an additional cost.  He's unfortunately not that good vs decks that run Crater's Claws even after you've locked down their 4-power creature.

Out of the sideboard, Dragonlord's Prerogative is Opportunity with upside vs Abzan and is relevantly uncounterable in control mirrors.  Ojutai's Command is great vs aggro/midrange creature decks and not a problem to cast with the mana base.  Counter/draw is often the mode of choice but occasionally you will get back a Nyx-Fleece Ram or gain life vs. aggro.

Since the deck needs a critical mass of dragons for Silumgar's Scorn, you can have two sideboarding frameworks.

For matchups where the main deck feels strong, you very often just side out Narset (except in control mirrors) and shave some Banishing Light, End Hostilities or Elspeth to bring in more focused cards (usually more specific removal or card draw).

For fast decks where the 5-drop dragons don't work well, you side out Icefall Regent, a Dig Through Time, an Elspeth and some number of counter spells.  Narset usually comes out too.  Bring in the sheep, Ojutai's Command, Encase in Ice, Surge of Righteousness and Aetherspouts and play a more conventional removal-heavy control deck.  I haven't run this configuration much (I feel more vulnerable these days without Scorn being straight-up Counterspell) but I think this is a legitimate plan.

Cards I would consider experimenting with - Arashin Cleric instead of sheep in a token-heavy metagame, Valorous Stance (a one-of in the main deck to protect dragons and kill big threats), ... not sure what else.  Targeted removal will become pretty important for resolved threats as Dromoka's Command sees more play and your Banishing Lights get sac'ed as a result of them.