Progression/Mythical
Written by demon_monkee on Leaf Blower Revolution Discord.
This will cover the most optimal way to get from 
The Mythical Garden to unlocking 
Obsidian Leaves. If you're before Mythical Garden, Progression/Strange Science will help you.
Key 
Gem Upgrades
It's Mine! becomes a lot more useful now, allowing you to keep certain useful tools like THE HIGHTECH DRILL and THE HIGHTECTH SHOVEL through prestige, as these are a pain to refarm.
All Leaves+ and Offline Profits +750% aren't as good here if you're following this guide, so i'd save your gems if I had Supporter Packs.
Trading - The Meta-Breaking Feature
Due to the massively high costs of future areas, grinding 
BLC for them will take a long amount of time, either several hours of manual farming or more hours of going offline. Luckily, there is a way to just entirely skip that, through Trading. Trading, as the name implies, allows you to trade leaves/flasks for other resources. The point is to turn useless leaves into more important resources.
This might seem fairly useless, however Trading allows you to get leaves you have unlocked without buying the area to get them. For example, if I bought the Unlock Lava Leaves upgrade in the 
Mythical Shop, even if I don't have The Volcano, I can still get 
Lava Leaves through Trading, regardless of me having never obtained a Lava Leaf.
However, even with this, you can't get more than a couple ten thousand leaves per trade. Well, that's because there is a cap on how many leaves you can get through Trading. You can only get up to 100,000(1e5) leaves per trade at base. This cap is based off which is higher: your all time earnings(slow to increase with trading), or with the Mulched Trade Caps upgrade in the 
Mulch Shop, which multiplies the trade cap by 10 each level. 
Mulched Trade Caps will be our main source of getting new leaf types since it's a lot easier to increase.
Progressing Through Leaf Types
First, buy these BLC Upgrades, if you haven't already:
- Buy Trading Certificate ( 100k (1e5) BLC) - This gives us access to Trading, which will be our main leaf gaining tool.
- Leaf Trader (1/3) ( 2m (2e6) BLC) - This allows us to get more Trades/cycle, giving us more options to get the trade we want.
- Trading Education (1/50) ( 20m (2e7) BLC) - This upgrade gives you access to Level 2 Trades, which have a higher input cost for higher rewards. It is used to get more Mulch, but you may not be able to keep up with the increased costs.
- Unlock Mulch ( 25m (2.5e7) BLC) - This gives us access to Mulched Trade Caps, an insanely powerful upgrade.
Penguino ( 2m (2e6) BLC) - This pet drastically lowers Trade time and decreases refresh time.
Your first step is to trade for Mulch. Equip Penguino and start Trading, picking up any Mulch trades that you can afford. With your Mulch, only spend it in Mulched Trade Caps. During the time where you have a mulch trade in every 
Trade slot, you can optionally pick up the 
Cheesetor Pet and start AFKing with that for some extra Cheese. Once you have 8 levels in Mulched Trade Caps, you can stop trading for Mulch. Now, we see the fruits of our labor - we can trade up to 10t(1e13) leaves in a single Trade(although rare). This is enough for the first level of the 
seed for every leaf type for the foreseeable future. Trade for 
Celestial and Mythical leaves and purchase the first level of both their seeds. Also buy Unlock Lava Leaves in the Mythical Shop. Then, do the same thing with Lava - purchase the first seed level and buy Unlock Ice Leaves. You know the drill - buy the first seed level for 
Ice Leaves and get Unlock Obsidian Leaves. There is something you can do while lying around waiting for these trades to finish - seed farming. It is relatively similar for Mythical - Ice as it is for 
Basic - 
Exotic. This will be further explained in the next section.
Seed Farming
In between trades for new leaf types, try to get at least some seed farming done. Equip 
Raccoono and turn off any 
Autobuyers for Mythical+ leaves. Be sure to max out the fertilizer upgrade for Mythical+ leaves ( Celestial is a bit different, explained later) for the maximum seed spawn chance.
You should have the 
Rainbow Leaf by now, so spend this amount of your current leaf count on the seed upgrade:
- Level 1: 100%
- Level 2-50: 1%
- Level 50-100: 0.1%
Celestial Leaf Seed Farming
Now, you may have noticed that 
Celestial Seeds are incredibly rare. Well, that is because they have no fertilizer, and thus spawn 50x less frequently than other seeds. Instead, you have a very expensive Seed Marketing upgrade, which can't be maxed off the bat.
Upgrade Seed Marketing when you have (upgrade number + 1)x the cost of the upgrade: for example, 2x leaves for lvl 1, 3x leaves for lvl 2, etc.
After unlocking Obsidian Leaves, congrats! You can now move on to Progression/Obsidian. Hopefully, you should have maxed at least a couple of new leaves, but don't worry, you'll be able to work on them later.