adventurers now acquire a ring while leveling. there's two challenges you get through Cassandra which allow you to get a ring.

the rings may work different in global. in kms you could only acquire one per character. if you wish to get them all you need to make new characters and start a new challenge. you could trade the ring ONCE via storage. while you can have all the rings in one characters inventory, you can only wear one at a time.

you also couldn't wear lilins rings with an adventurer ring on.

selection:
challenge one-
If you level up 30 times from your current level, you can get the adventurers cruel ring from cassandra.

challenge two-
If you level up from Lv. 1 ~ 50, you can get the adventurers cruel ring or adventurers critical ring or the adventurers magical ring.

(in kms you had to make a new character to acquire the ring, old characters cant simply talk the npc and get a ring)

Adventurer’s Cruel Ring
REQ LV: 30
Weapon Attack: +3
Magic Attack: +1
HP: +180
MP: +100
Has a 1% chance to instant kill 1 enemy
5% chance of dealing Critical Damage (20% Damage)

Adventurer’s Critical Ring
REQ LV: 30
Weapon Attack: +2
Magic Attack: +1
HP: +180
MP: +100
Has a 1% chance to instant kill 1 enemy
10% chance of dealing Critical Damage (10% Damage)

Adventurer’s Magical Ring
REQ LV: 30
Weapon Attack: +1
Magic Attack: +5
HP: +100
MP: +180
Has an 8% chance to stun an enemy for 6 seconds
5% chance of dealing Critical Damage (20% Damage)

Read the directions, and directly you'll be directed in the right direction.