After obtaining the pendant from the previous step, teleport to Botany Paradise Northern section. Advance through the left with the following route.

You will need to go through the following maps:
Botany Paradise Northern Section
Deserted Weapon Testing Field
Hidden Arsenal
Bridge Linked to Bastea Gate.

Inside Hidden Aresenal, you will have to defeat some enemies to obtain their keys before advancing through the locked doors.

Make sure that you enable the teleport before you leave Bridge Linked to Bastea Gate.

You are told that you will have to defeat the area boss plus the pendant to advance through to the next area. With nothing else to do, you are given a clue to check out the temple area.

Head toward the Temple of the Offerings, kill the boss. To make this boss easier, you should use gears with decent vit and defense so that you can tank through his attacks. After defeating the boss, exit out of the temple to encounter some story. You will regain control of your character back in the control area.

With the Hollow Jewelry of Illumination and the boss dead, head back out to use the teleport device towards Bridge Linked to Bastea Gate to unlock the sealed gate.

Shortly passing to the Floating Ruin of Plaza at Bastea. Walk straight to face yet another seal. You are given the clue to obtain some dragon treasures. Now, you have several paths that you can take at this point. Follow the path below to obtain the Testament of the Dragon King.