Here is the full list of all 21 Arelite Core achievements.
Defeat Eron, Thalasai Monastery's invader
Defeat 100 monsters
Leave Arreal and set off on your adventure
Defeat Kiori, Tempest Tower's invader
Defeat Gharell, Oda castle's invader
Defeat Iana, Talameq's envoy
Defeat Talameq and save the world
Defeat 250 monsters
Defeat 500 monsters
Deal 9999 damage with a single attack
Stun 100 monsters
Combo crash after a 50 hit combo
Use Baeme's tinker ability to craft every type of weapon once
Use Aurek's summon ability to invoke each monster once
Enter every regular monster type into the bestiary
Take 25 000 steps
Gather 100 000 ing at once
Complete the game under 10 hours
Forge a weapon at the highest smithing level
Collect every plush toy in the game
Overcome the greatest threat, the Awoken Dragon!