Trove

These achievements are incredibly grindy (mainly Further Heights), so you'll have to either play (or pay) quite a bit to get them. Each rank requires 100 points (and gives you some stat buffs - specifically +10 Light and +5 Power Rank per rank, for a total of 1,000 Light and 500 Power Rank at Geode Mastery 100).

You can also run /geodemastery at any time you get a full breakdown of its points. Mostly used to check the amounts of things (e.g. you've crafted 10/25 mounts (or whatever the amount is)), but it also lets you check your exact point count if you care about that.

If you're friends with someone who's fairly late into the game and has either quit or is willinlg to help, have them give you some of the more expensive items that give Geode Mastery. You can view the tooltips for exact amounts, but costumes generally give the most. This is pretty rare though, but it will save you a massive amount of time. Worth asking around to see if anyone has spare Geode items they don't want (even if it's just resources).

You can earn Geode Mastery from the following:

• Styles (1 point each, but some give 10)
• Recipes (2 points each)
• Alliies (50 points each. Called "Companions" in Geode)
• Tomes (20 points for regular ones, 100 points for legendary ones)
• Costumes (varies)
• Mounts (50 points each)
• Wings (100 points each)
• Professoin tiers (75 points each). There's only 1 professsion in Geode: Crytsology. That's where you'll get almost all the mastery items, so it'd be good to max it along the way.
• Equipment upgrades (50 points each). I'm not sure if there's a limit on these, but at minimum the limit is level 10 since that's the max for geode equipment.

To earn geode mastery points, simply go to a Crystology Table and craft all the items in it that give mastery. There's also everything from the crafting station in the Delve section of the hub (I can't remember its name though). Craft everything from it first since they're cheaper, and give you a nice headstart (you can use some of the items you get from Geode Mastery to earn more Geode Mastery). You'll need a lot of Crystals, which are untradable - however, other resources are tradeable, so don't be afraid to buy some off the marketplace if you need them.

While crafting will be your main source of Geode Mastery, you can also hatch Companions (the eggs of which can be found in Geode Caves, albeit rarely). This method is quite slow due to how random it is (I'm still missing half a dozen or so of them), but it does give you a decent amount of points.

The third method is upgrading your equipment. You'll want to do this anyway to progress through Geode Caves (get the Vaca-Matic to level 10 as soon as you can. It'll make everything else way easier), and each upgrade gives you 50 mastery points.

As I said at the start, it's an incredibly grindy process (took me 3 - 5 years) - but it does give you an important stat and a decent amount of items (in addition to bragging rights for your achievement showcase on Steam).