Game Breaker / Rune Factory 3

• The Sharance Maze under your home. Accessible once you beat Raccoon in Privera Forest, it provides the player with obscene amounts of money, item drops, experience and skill grinding, all with no penalty if you faint when using the wireless multiplayer option. To top it off, on multiplayer mode, no time passes at all and you can play as any character other than Micah, getting their individual benefits with the added plus of not losing money if you faint there. Sadly, multiplayer mode is not available in Special remaster, but the Sharance Maze still remains a very good source of items.
• As mentioned above the original version of 3 allowed you to select which villager you wanted to play as. Each villager would carry their preference in food and if they liked a type of food with Double-Edged Buff they wouldn't get penalized by it. A prime example is Sofia who would get healing and massive stat boosts from Super Fails (Disastrous Dishes) and Pia who would get all of the powerful benefits of Prelude to Love (damage reduction from all sources) without losing 50% or more of her Max HP.
• High-level hammer + Millionstrike or Grand Impact skill seal + Lucky Strike = Kill anything that isn't a boss in one attack (Or kill anything that isn't a Sharance Maze boss in four).
• Oil + Explosion spell = Anything that doesn't absorb fire magic dies in five shots or less. Anything.
• Scrap Iron, believe it or not. It's incredibly difficult to work worth, beaten only by Platinum from ores. This means that once you're able to, you can make useless gear you plan on selling and... *ahem*...upgrade them. You get a ludicrous amount of experience for using them as upgrade materials, and the value of the item being upgraded (surprisingly) goes up. And it probably helps by being more common than dirt. Just make sure not to give them to anyone or use them yourself (even if the lowered stats aren't that bad).
• Cooked dishes in general can be this, thanks to their percentage-based HP and RP recovery and the temporary stat buffs provided, but some can be pretty ridiculous:
  • You can make Bamboo Rice almost as soon as you unlock the kitchen. It's made with Bamboo Shoot and Rice, and both are very easy to get (especially on Spring, as your farm's field grows Bamboo Shoots). Its HP recovery is 40% and its RP recovery is 50% (and that's not counting its other bonuses), quite high for a level 10 recipe. In short, just by eating 2 of these, you get your RP (and possibly your HP) completely restored.
  • Pudding is another good recipe, though it requires a higher level. You just need a Cooking Level close to 30-35, a Steamer and just 1 of any egg. You temporarily lose 20% of your max HP, but it recovers 80% or your RP. If you make it with an egg of a larger size and/or higher level, the pudding's level becomes higher as well, and at higher levels, its RP recovery easily exceeds 100%.
  • Pound Cake is another good example being easily made with one Flour and one Egg. It recovers a hefty amount of HP and RP while increasing maximum HP. It's only offset by demanding a pretty high Cooking skill level (50/52/54).
• Equip an Element Shield^* halves fire, water, wind and earth damage, a Magic Earring^* halves light damage, and an Art of Magic^* halves non-elemental physical damage, but not before upgrading two of them until they get at least 50% resistance to Dark and Poison combined. After that, eat a Prelude to Love^* its temporary buff cuts your max HP and RP by half, but halves all damage done to you. Congratulations, you just made Micah able to take at least almost no damage whatsoever from most attacks. To make this setup even more broken, play the multiplayer Sharance Maze as Pia. As Prelude to Love is one of the things she likes, she won't get the max HP/RP penalty, while still getting its benefits.
• A Sun Pendant with Levelizers can bring all but Mystery Maze from Sharance Maze to its knees. Sun Pendant on Micah gives a huge boost in statuses for any villager in his party. Levelizers, made with 4-Leaf Clovers, will instantly grant them an instant level up and can be produced once your Pharmacy skill is high enough. Make the villager of choice level up enough, get them properly equipped and all you have to do is stand back and support your ally while they destroy everything in their path, and if they're sufficiently strong they can solo bosses. The only hurdle to overcome here is reaching high enough in Pharmacy skill (89) to start mass producing Levelizers.
• Staff crafting can give you some potent effects. Certain materials like Panther Claw and Dragon Fang give very strong effects that can destroy easily anything that's it hits.
  • Panther Claw is a quick charge spell that unleashes a short range claw attack that hits a lot of times. The material is easily accessible once you open the gate in Sol Terrano Desert in the main story too.
  • Dragon Fang stands out, though: its charge magic is somewhat slow, but that can be easily circumvented by equipping a Magic Ring, and when fully charged it lets out a very potent, if somewhat short-ranged, fire breath that annihilates anything that isn't fire resistant. And if it is? Use a cooking Oil like the above mentioned example. Only the rare fire element absorbing enemies, and Fiersome, can withstand this attack. The cherry on top of this sundae is that unlike boss-only materials this attack doesn't use up a massive amount of RP. The sole problem is that this materials is only found at the last dungeon of the main game, or the later parts of Sharance Maze, but once gotten even other Sharance Maze levels can be a breeze.