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
Acquire every skill from Loretta.
Find, collect and sell all 20 relics to Yombal.
Complete the 6 challenge stages.
Defeat Imbra the Shadow Sorceress.
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.
Chain zap 7 enemies with lightning magic.
Starting with an uppercut, perform a full aerial combo with any Crimson weapon.
Perform a full plummet combo with any Crimson weapon.
Defeat Kravios the Aquatic Voltknight.
Using the sword, pogo-bounce on 4 separate enemies without touching the ground.
Defeat Bora the Whirlwind Assassin.
Acquired your first skill.
Have a throwable rock bounce on an enemy 5 consecutive times without touching the ground.
Defeat a training dummy in Sanctia.
Find and collect a golden relic.
Set out on an adventure with your beloved friend, Dex.
Quickly skip Bohrin's dialogue.