Satisfied Condition

According to an ancient document that I deciphered, those who used the Sky Bridges would offer a sacrifice and then use a medium to summon the elemental residing in the bridge. In other words, the bridges moved by using the power of the Elementals, right? But instead of using the power of the Elementals as a medium, the document mentioned something else. I will give you the list now, so make haste and return with all of them as soon as possible.
What I need are <HFFFA7272>4 Rotten Stems<HFFFFFFFF> that can be obtained by using <HFFFA7272>Collecting Skill<HFFFFFFFF> on the Rock Torges in the <HFFFA7272>Lands End<HFFFFFFFF>. Please hurry.

Obtain <HFFFA7272>4 Rotten Stems<HFFFFFFFF> by using the <HFFFA7272>Collecting Skill<HFFFFFFFF> on the <HFFFA7272>Rock Torges<HFFFFFFFF> in the <HFFFA7272>Lands End<HFFFFFFFF>. You must not miss a single thing!

Good. Now using this medium... using... using.. Hrm, how am I supposed to use this? The document only mentions a medium and nothing about how to use it. What should I do now? Hmm... I'm sorry. I was really eager to see the Sky Bridge move again. I'll have to look into other documents and contact you when I find something.