Here is the full list of all 22 Flynn: Son of Crimson achievements.
Have a throwable rock bounce on an enemy 5 consecutive times without touching the ground.
Completed all levels, acquired every relic and learned every skill.
Find, collect and sell all 20 relics to Yombal.
Find Bax in 4 separate locations.
Quickly skip Bohrin's dialogue.
Have an enemy frozen, burned and zapped simultaneously.
Acquire every skill from Loretta.
Complete the 6 challenge stages.
Defeat Zealock
Defeat Imbra the Shadow Sorceress.
Perform a full plummet combo with any Crimson weapon.
Set out on an adventure with your beloved friend, Dex.
Defeat Bora the Whirlwind Assassin.
Defeat Kravios the Aquatic Voltknight.
Defeat Xellios the Toxic Marksman.
Defeat Rozia for the final time in the Desolate Woods.
Find and collect a golden relic.
Acquired your first skill.
Starting with an uppercut, perform a full aerial combo with any Crimson weapon.
Chain zap 7 enemies with lightning magic.
Using the sword, pogo-bounce on 4 separate enemies without touching the ground.
Defeat a training dummy in Sanctia.