The best farming method here would be through beating up Aquatanks and Screwdivers found in the more open areas of Atlantica. The reason is because they’re easy to defeat with little effort, and they’re plentiful to farm. Bambi is another option, however this requires filling up 3 charge gauges just to get a chance at a drop. So if you can put up with more time in Atlantica, it’s really your strongest option for Thunder Gems. And these gems are pretty important for a slew of synthesis recipes in the game – including the Ultima Weapon!
Thunder Gem Farming
There are a few decent options here, with Atlantica being the best place to go. But let’s take a look at every method you can use to get your hands on these gems in KH1 + KH1.5.
Screwdivers
These are the stealthy diving soldiers found lurking in Atlantica. With their 6% drop chance (4% in Final Mix), these guys are really your go-to for farming Thunder Gems – alongside Aquatanks which are usually found in the same location. If you disembark in Triton’s Throne Room and leave the palace from there, you should run into lots of Screwdivers. Then you can spread out to the open area just outside the palace to find even more of these guys. Farming in Atlantica can be difficult since it’s such a confusing world to map out. But it’s also easy enough to hit the save spot, leave the world, then re-enter to keep farming Screwdivers in the same spots repeatedly.
Aquatanks
These are the big bulky sea creatures also found in Atlantica. They look like big rounded fish and often have Screwdivers hanging off them. Even though they’re pretty bulky with lots of HP, they’re still quick to take out. And they have a 10% drop chance (8% in Final Mix) for Thunder Gems – which is pretty good! These usually spawn alongside Screwdivers, so again you can disembark in Triton’s Throne Room and try farming in the areas around there.
White Mushrooms
We all know these mushrooms by now. They play charades, you cast the right spell, and if you get them all right you get some prizes. For Thunder Gems you’ll need to cast Thunder spells (big surprise). If you cast 3 correct Thunder spells in a row, then you have a 60% chance (10% in Final Mix) to get a Thunder Gem from these mushrooms. Or if you just make sure that Thunder is the last spell you use, then these guys have a 20% drop chance (0% in Final Mix).
Bambi
Bambi comes with a charge gauge that you fill up by defeating Heartless. If you summon Bambi in Deep Jungle and manage to fill the gauge three times, he’ll have a 30% chance (20% in Final Mix) to drop a Thunder Gem. Just note that this strategy only works in Deep Jungle, because Bambi’s drops change depending on the world you’re in. Here’s a quick look at what Bambi can drop in Deep Jungle, depending on how many gauges you can fill.
Thunder Gem Uses
These gems are required in a bunch of synthesis recipes, some more useful than others. Here’s a quick list of everything you can make that requires Thunder Gems. Mega-Potion: Heals 30 HP for every party member. You can make this in the original KH1 with List II and x1 Blaze Gem, x1 Thunder Gem, x1 Frost Gem, and x2 Mythril Shards. The KH1.5 Remix recipe is different and doesn’t need any Thunder Shards. Mega-Ether: Similar to the potion above, this will restore 3 MP for each party member. Make this in KH1 List III and x3 Blaze Gems, x3 Frost Gems, x3 Thunder Gems, x5 Bright Gems, and x1 Bright Crystal. Again, KH1.5 has a different recipe without any Thunder Gems. Rune Armlet: Enhance your magic and summon power with +1 MP and +1 Defense. You can synthesize a Rune Armlet in KH1 with List III and x2 Blaze Gems, x2 Thunder Gems, x2 Frost Gems, x3 Mythril. If you’re playing KH1.5 Remix, then the recipe will instead need List II and x3 Blaze Gems, x3 Frost Gems, and x3 Thunder Gems. AP Up: Increase any party member’s AP by +1 point. You can synthesize this in KH1.5 Remix using List III and x2 Blaze Gems, x2 Frost Gems, x2 Thunder Gems, and x4 Mythril. Ribbon: This is one of the best accessories in the game, granting you +20% resistances against Fire, Blizzard, Thunder, and Dark, as well as +3 Defense. You can even equip more to increase the effects. Synthesize one of these (or more!) in KH1 using List IV and x5 Blaze Gems, x5 Frost Gems, x5 Thunder Gems, x5 Bright Gems, and x3 Gale. But if you’re playing KH1.5 Remix, then you’ll need List V and x5 Blaze Gems, x5 Frost Gems, x5 Thunder Gems, x1 Gale, and x3 Serenity Powers. Ultima Weapon: Speaking of great items… with Thunder Gems you can forge the best keyblade in the entire game! The Ultima Weapon offers +12 Strength (+14 in Final Mix), +2 MP, and a great critical strike chance. It’s a must-have synthesis item. In KH1 you can make this with List V and x5 Lucid Gems, x5 Power Gems, x5 Thunder Gems, x3 Mystery Goo, and x3 Gale. In KH1.5 Remix you’ll need List VI and x5 Thunder Gems, x5 Mystery Goo, x3 Serenity Powers, x3 Stormy Stones, and x3 Dark Matter.
Are These Worth Farming?
Thunder Gems are used in so many powerful recipes. And you probably want to craft the Ultima Weapon as soon as you can. So it’s definitely in your best interest to farm these gems and gather as much as you’d need (probably around 10-15 to synthesize each recipe once). Several trips around Atlantica should net you a fare bit, as long as you’re searching every nook and cranny for Screwdivers and Aquatanks. And you can always optimize this farming process to plan routes for the quickest drops, then just leave the world & re-enter to repeat the process.