Alright, so I'm going to be providing feedback on both the deck and the primer itself.
Primer first. You've only really scratched the surface of what a primer is supposed to look like. It's supposed to be a guide on how to play a certain deck, strategy, or commander. At minimum, it needs to include a description of the game-plan, how the deck wins games, and then discussion on why you included certain cards and excluded others. You should (but don't necessarily need to) include other things like the deck's strengths and weaknesses, budget or more expensive alternatives, and starting hand selection. You should also include what kind of games this deck is meant for. Is this a budget deck? Is it meant to be an example of a strong Ur-Dragon deck.
While you did include the first three parts, they're scattered around the primer and they're all lacking substance. You explained that in the early game you're going to be playing cards with defender to serve as blockers. Then what? Is combat damage the only win-condition, and if so, do you have any suggestions on how the pilot should go about this?
You've listed a lot of the cards you're using, but you didn't list why you're using them as opposed to any of the other cards you could use. Why are you using those three cards from the command cycle as opposed to the other 7? Or instead of the other options you have for removal/protection? Likewise, you listed cards you're excluding, but not why. Why aren't you using
Niv-Mizzet, Parun? It seems like a good fit for this deck. You don't need to include these cards just because I think you should be using them, but you do need to explain why that card isn't a good fit. Is the mana cost too restrictive? Is it outside the deck's budget? Or does the deck already have a card that works better than that choice.
This primer is going to need a lot of polish. I would recommend looking at the format that other primers use, and do something similar. Some examples.
These are good general formats for primers. You're welcome to do your own thing, but it should have some sense of structure so readers can navigate to different parts. Sometimes they're going to be working on their own Ur-Dragon list, and they just want to know why you choose a certain card, so they can figure out if they should use it. Or they are going to want to see what your combo/win-condition is so they can try to improve their combo/win-condition. The reader should be able to easily
jump to these sections.
Now onto the decklist. A big thing I see is that you're trying to do multiple things at once instead of focusing a strategy. You want to do dragon tribal, +1/+1 counters, and creatures with defender. Focusing your strategy will do wonders for this deck.
I still don't understand why you want to include so many cards with defender. The reason you gave is because the deck is slow so you need to defend yourself in the early turns. But most of the creatures with defender don't have reach or flying and the dragons have better power and toughness. That and they have no synergy with
The Ur-Dragon, so the dragons are just all-around better for this task. Wouldn't it be better to include mana ramp and card draw so you're not as slow in the early game, or just include more dragons as they are better blockers and have synergy with the deck?
Belltoll Dragon,
Herdchaser Dragon, and
Shieldhide Dragon are all part of a cycle that also includes
Acid-Spewer Dragon and
Stormwing Dragon. Do you also want to include these cards?
The deck has very little mana ramp or card draw and has a high curve. Around what turn can you get
The Ur-Dragon onto the battlefield? How often do you end in top-deck mode?
I'd also like to know why you're not using these cards.
Arcane SignetAtarka, World RenderChromatic LanternDragon's FireDragon's HoardDragon TempestDragonlord's ServantHaven of the Spirit DragonHellkite ChargerHellkite CourserHerald's HornKindred DiscoveryKindred SummonsOrb of DragonkindSavage VentmawScaled NurturerScourge of ValkasSecluded CourtyardSol RingSunscorch RegentI'd also like you to explain why you're using these cards.
Arvad the CursedAtla Palani, Nest TenderChorus of the ConclavePerimeter CaptainSouls of the Faultless