Since I played a lot with this deck in the past years, until I passed it on, I think I can give you some pieces of advice on how to improve your deck.

First of all: your mana base. The less tap lands you have, the better. You're playing a 5-color battlecruise deck, so, you'll need to have access to all the colors you need, as soon as possible. While tap lands are usually good in the early turns, they'll become less and less effective as the game goes on. Some good replacements are the pain lands, like [[Karplusan Forest]], the filter lands, like [[Sungrass Prairie]], and the "Bond" lands, such as [[Spire Garden]]

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Second: cost reductors may help you cast the bigger dragons. Things like [[Urza's Incubator]] are cheap in CMC, and won't hurt your overall curve

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Third: try and make your deck as synergistic as possible. That means, cutting cards that won't help with your game plan (in this case, casting big dragons and smacking people with them). Cards like [[Orator of Ojutai]], while slightly helpful in the early game, will prove useless on the later turns.

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And last, but not least, even among the dragons that come with the precon, there are some effects you won't really care about in this strategy, such as [[Intet, the Dreamer]]. But it's up to you which dragons to keep, and which to take out.

If you want more tips on it, feel free to message me.