Here is the full list of all 23 RUINSMAGUS: COMPLETE trophies - there are 8 bronze, 6 silver, 8 gold and 1 platinum.
Complete All Other Trophies
Start your first quest in the Ruins
Buy an Attack Up item from the Shop
Use an Ult Attack for the first time
Enhance your gauntlet for the first time
Become an Expert Magus
Encounter a mythical creature in the Ruins
Defeat a group of Rogues for the final time.
Help Orfeo and Euridice for the final time.
Get kicked out of the 'weird club'.
Team up with Ryuuki.
Become a Master Magus.
Find all the Clavis Stones.
Complete the main story.
Defeat the mysterious tailor
Clear 5 Quests with an S ranking.
Clear 10 Quests with an S ranking.
Clear 20 Quests with an S ranking.
Clear 15 Quests with an S ranking.
Clear every quest with an S Ranking.
Unlock all the skills, charge and ult attacks.
Try out your skills by competing in the Meister's Abyss
Achieve a score of 25,000 or more in Meister's Abyss