Reanimator Package:
Buried Alive
Reanimate
Animate Dead
Exhume
Dread Return
Rise from the Grave
Frantic Search
Faithless Looting
Dragon Mage
Reforge the Soul
Windfall

Chandra, Flamecaller

Bear Umbra-like Cards: 
Sword of Feast and Famine
Nature's Will

Adds (Combos):
Moltensteel Dragon + Skithiryx, the Blight Dragon + Scion
Curiosity + Niv-Mizzet, the Firemind +Scion
Niv-Mizzet, the Firemind + Ophidian Eye or Keen Sense + Scion
Aggravated Assault + Savage Ventmaw + Scion

Cuts (Creatures):
Apprentice Necromancer (just bad)
Necrotic Ooze (only run if you are using Buried Alive or Wheel of Fortune effects, keep if you go reanimator route)
Dromoka, the Eternal (not that great, not a combo piece)
Dragonlord Silumgar (a lot of your other dragons focus on killing there creatures, you might not have something to steal)
Hellkite Charger (if within budget, cut for Scourge of the Throne)
Rubblehulk (not that great)
Ryusei, the Falling Star (Scion does "die" when you put him back in command zone)
Furyborn Hellkite (but a big guy, not necessary)
jutai, Soul of Winter (not that great)
Draco (bad)

Cuts (Non-Creature):
As Foretold (Only good if you are playing lots of spell on other's turns, better rocks available)
Propaganda (no need to pillow fort, you got big dragons)
Ghostly Prison (^)
Palace Siege (its just a bad card)
Monastery Siege (^)
Kindred Discovery (there is better draw for cheaper)
Frontier Siege (better rocks exist)
Prismatic Geoscope (you might not end up with a ton of basics in a 5 color deck)
Nihil Spellbomb (not enough room in 5 color for gy hate, you can run bojuka bog in place of a swamp)
Mirror of the Forebears (cut for Shapesharer which does the same thing but is already a dragon for those effects)
Reverse the Sands (just a bad card, any time you spend 8 mana, you should win the game)
Arcane Denial (if you are going to run 1 counter, it should be better than this)
Opal Palace (not good, only helps to cast general, need to make room for better lands)
Cascading Cataracts (not good)
I would cut all the bounce lands (i.e., Azorius Chancery)

Non-Budget Adds:
Gilded Lotus
Tooth and Nail
Sylvan Library
Vampiric Tutor
Demonic Tutor
Rhystic Study


All Shocklands
All Fetchlands
If you run shocklands then change ramp cards to:
Nature's Lore
Skyshroud Claim

Adds:
Chromatic Lantern
Fellwar Stone
Fact or Fiction
Recurring Insight
Search for Tomorrow
Phyrexian Arena
Diabolic Tutor
Elvish Piper
Mirari's Wake


Mana Base:
Clifftop Retreat
Dragonskull Summit
Drowned Catacomb
Hinterland Harbor
Isolated Chapel
Rootbound Crag
Sulfur Falls
Sunpetal Grove
Woodland Cemetery
Battlefield Forge
Caves of Koilos
Karplusan Forest
Llanowar Wastes
Shivan Reef
Sulfurous Springs
Underground River
Yavimaya Coast
Graven Cairns