The second stage(Elin PQ)

In this room, there is a huge tree with a bulbous green growth near the base.

As you enter, numerous Poisoned Stone Bugs will spawn. Lure them to the green growth first before killing it. Killing it before it is at the green growth is useless.
The bugs have a Super Weapon Defense Up, a buff that negates all physical attacks. However, this skill is pretty useless as it is not much of a liability and it holds up for a very short period of time. The stats of the Poisoned Stone Bugs is as following -

Poisoned Stone Bug
Level: 65
HP: 7,200
MP: 100
Avoid: 0
Knockback: 1,200
EXP: 255
Once you kill them, they might drop a useless Purple Poison bottle that can't be picked. Once dropped on the green growth, a Pink Diluted Poison bottle will appear. You only need 4 of them. Once you have 4 of the Pink Diluted Poison, go to the most right of the map and you will see a green thornbush. Drop the Pink Diluted Poison there ONE by ONE.
The thornbush will eventually disappear and you can go on to the next stage.