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