To become a Quincy in the game Peroxide, follow these steps:

1. Reach at least level 15 in the game.
2. Go to the Castle of the Wandenreich and find Yhwach, who is sitting on his throne.
3. Talk to Yhwach to become a Quincy and obtain the Schrift ability. You need to have a positive reputation with the Wandenreich to do this.
4. After becoming a Quincy, focus on training your stats, especially agility, to unlock abilities like flash stepping.
5. Progress by doing quests, training in the dojo, and participating in invasions to gain levels and stat points.
6. At level 90, allocate 420 points and then talk to Yhwach again to fight his minion and unlock Vollständig mode, which grants powerful buffs and abilities.

Additional tips:

• Avoid doing invasions too early; wait until you have a higher rank.
• Focus on either spirit or strength stats to optimize your build.
• Use Product Essence to reroll clan and Schrift abilities for better customization.
• Use the dojo to increase your stats efficiently and gain XP multipliers (stars).

This method is considered the fastest and most effective way to become and progress as a Quincy in Peroxide