Anyone who uses potions knows what a pain it can be to haul them around. They don’t stack and they take up a large amount of inventory space that could be better spent on carrying new loot. GemBuffs is a relatively small mod that does a huge favor for anyone who has to carry those potions around. It creates a reusable gem that gives the user a potion effect and recharges over time.
While this might seem game-breaking, there are a few things that balance it out a bit. First, the gems are as rare or perhaps more rare than diamonds. Along with that, they spawn deep underground in small veins. All of the potions used in crafting must be at max length, and many of the other ingredients that go into the gems are incredibly expensive on their own. These are definitely endgame items—something that you’d craft just before going into the End.
The only real way these gems would be unbalanced is if they were included in a modpack where there are alternative types of ways to make potions. They would be rendered useless or redundant by this mod. Since potion mods are few and far between, this isn’t a big problem in regular modpacks. In fact, I would say that GemBuffs actually keeps potion effects relevant in modpacks where technological armor and mining efficiency are the main play style goals.
The potion effect that the gems grant varies depending on what potions you used to make it. All potion effects—as well as some other effects that are less frequent in mods—make an appearance. The ones I find most useful are the Gem of Celerity and Gem of Salubrity. They are perfect for the types of players who just want to go exploring. Unfortunately, you can’t just combine any potions to create a custom GemBuff. While it would be hard to code, it might add an interesting layer to the mod and make it stand out from the others. Right now, it seems as if the features are at a standstill. Seeing how futhead_wiiboy222 (the creator of the mod) expands on it will be exciting.
Overall, GemBuffs is a small mod that adds just a little bit of flavor to vanilla. Even if you place it in a modpack with many other different mods, it should still remain relevant. It is very small, but its utility is worth considering if you find yourself using potions all the time.