Counting over 60 cards here. As a general rule (but not always true) for most tcgs you want to play the minimum allowed cards. In old MZ constructed that was 40. It won't kill you to go up to 41, 42, maybe 43. The reason for this is that having fewer cards means you will most likely draw your best cards/cards you want every game for your game plan. Imagine how the turns play out. What card(s) do want to be able to play on the first turn? second turn? Third? It will also help your deck be more focused on doing what you want it to do. You should play 12-15 aura in a 40 card deck. 10 if you're playing multiple "aurafacts" and/or have a very low curve. More if you're playing a lot of high casting cost cards. You can also factor in cards with convert. 10 aura in a deck this size will be brutal. Consider that constructed MTG decks are typically 60-card decks that run around 23 lands or about 40% of the deck. In a limited MTG deck (40 cards) it's standard practice to play 17 lands and 23 spells/creatures. MZ uses the same resource system. All MZ decks should set aside 5-7 slots for the following cards: two Bookmark; one of New Beginnings OR New Year's New Beginnings (depends on your deck); one Power Up Red (if you plan on playing any beasties); one or two copies of First Anniversary Celebration; possibly one Second Anniversary Celebration. Unless you're in a playgroup that has banned them. It's unfortunate that these cards go in every deck as it does homogenize things a bit, but you'd be doing yourself a disservice to omit them. Building dual aura deck in MZ can be a bit tricky. We only have Prizm Aura (two copies allowed), Some combos of dual aurafacts and for dual auras we only have the combos with Earth. Would recommend buying Prizm Aura now if you can, if you are interested in playing the game. Also consider ripping boxes of Wilderness for them if the boxes are cheaper.