2xp for multiple characters on Black Ring:
First, equip the Black Ring on one character (Baldren for example) and enter a battle. When the battle ends, un-equip the ring from Baldren and give it to another character. Both characters will continue receiving double xp until you exit the game or you change any form of equipment on any of your characters.
Re-roll hidden loot:
When you find a "???" Hidden Loot the type is usually set in stone, but the amount can be manipulated. If you get coins you can "cancel" out and re-select the hidden loot several times until you "roll" the maximum possible number of Rainbow Coins. Same for potions. Occasionally you find one potion, but there is a possibility to get 2 or 3. Simply cancel a couple times and re-select the Hidden Loot to maximize your findings.
Bathe in the Well - Use any recovery well at least 15 times.
Bear Up! - Accumulate 40 hours of play time.
Camper - Use the camp at least 25 times.
Charged Magnet Coil - Obtain the Charged Magnet Coil artifact.
Compulsive Hoarder - Obtain at least 100 hidden treasure items.
Crafting Novice - Improve your weapons or armor at the crafting shop for 10 times.
Crystal Clasp - Obtain the Crystal Clasp artifact.
Don't Worry, Be Happy! - Lose three battles.
Dozeru - Acquire Dozeru.
Ethereal Spike - Obtain the Ethereal Spike artifact.
First Victory - Win your first battle on Rainbow Moon.
Forgotten Island - Discover and enter the Forgotten Island, an optional area on Rainbow Moon.
Fused Twilight Gem - Obtain the Fused Twilight Gem artifact.
Gambling Expert - Win five 'Class-A' prizes in the lottery.
Gorodo - Acquire Gorodo.
Hit and Run Fighter - Win 50 or more random encounter battles.
Level Fan - Reach level 100 with any of your main characters.
Limwar's House - Discover and enter Limwar's House, an optional dungeon in the Green Shimmer Forest.
Lucky One - Win 10 prizes in the lottery.
Magic Socket - Obtain the Magic Socket artifact.
Mojo of Tears - Obtain the Mojo of Tears.
Mojo of Torture - Obtain the Mojo of Torture.
Mojo of Trust - Obtain the Mojo of Trust.
Monster Cutter - Create 100 new monsters by tiling existing monsters with the killing stroke.
Monster Farmer - Kill at least 300 of the same type of monster.
Murky Basement - Discover and enter the Murky Basement, an optional dungeon in Burning Steppe.
Noble Tourist - Stay overnight at the tavern 10 times.
Ocher Stone Swamp - Discover and enter the Ocher Stone Swamp, an optional area on Rainbow Moon.
Orb of Delusion - Obtain the Orb of Delusion artifact.
Passive Skill Fan - Learn at least 10 different passive skills with any of your main characters.
Pro Crafter - Improve your weapons or armor at the crafting shop for 50 times.
Rainbow Pearl Collector - Accumulate 200 Rainbow Pearls with any character before spending them at the savant.
Rich? - Accumulate 2,500 Rainbow Coins in your inventory.
Sarrothrod's Rescuer - Help Sarrothrod in the Southport Mines to escape from the dungeon and return to Cassar Village.
Scaredy Cat - Escape 30 times from a battle using the escape option.
Serena - Acquire Serena.
Side Quest Master - Complete 40 side quests or more.
Trisha - Acquire Trisha.
Twisted Pole - Obtain the Twisted Pole artifact.
Warehouse - Discover and enter the Warehouse, an optional dungeon in Taswan.
Well Boss Killer - Defeat the monster that lives in the well in Cassar Village and get back to Stella.
Well Explorer - Discover and use all wells on Rainbow Moon.
Bulls Eye - Win two 'Class-S' prizes in the lottery.
Everlasting Perfectionist - Accumulate 100 hours of play time.
Extreme Crafter - Improve your weapons or armor at the crafting shop for 250 times.
Half a Millionaire - Accumulate 500,000 Rainbow Coins in your inventory.
Level Master - Reach level 250 with any of your main characters.
Level Up - Level up any of your active skills to level 50 or higher.
Make Friend - SAcquire all six main characters.
Skilled! - Acquire and learn all available skills for any of your main characters. (The skill level doesn't matter)
Dimension Traveler - Rebuild and obtain the Magic Portal Staff and defeat Namoris for the last time to gain unlimited warp access to the portal.
Level God - Reach level 500 with any of your main characters.
Official Rainbow Moon Hero - Earn all Bronze, Silver, and Gold trophies.