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