This is a simple guide on how to do Orc's Memory dungeon.

Note: This is not a guide on how to do it easily but rather just to help you know what are the things you need to know and prepare when going to this instance.
Opening the instance

- You need to talk to this npc located at (@warp gef_fild10 240 198). You can access this map by talking to the npc warper.

Must be a Hero.
At least 2 people in party online.
(party mate doesn't need to be a hero)

The instance has quite a low difficulty but it will require you quite some stuffs.
In my opinion the best thing you need to prepare here is cloaking skill.
Followed by anti knockback stuffs for boss.
FCP will help you too against the boss.
Only 2nd skill work in this area.
Mastela Fruit and Yggdrasil Leaf doesn't work in this instance.

Most veterans can run and finish the instance in 5 minutes or so.
It can be repeated every 2 hours or by using a different character in your account to spam it.
(at this point there's no account bound restriction on it)

Exploring the Instance

Once you are inside the instance, you'll notice an orc standing there.
Talk to him and wait until he finish his pretty long monologue.

The NPC will explain to you that you need to "sneak" and "assassinate" Enchanted Orcs on each area.
Killing them will trigger the opening of portal that will lead you to the next area.
This is also the reason why you need the "cloaking" skill here if you want to do it faster.
There are 4 areas in total in the first floor.

Note: Killing extra mobs will alert the leaders and they'll prepare an army to block you.

The first enchanted orc is located in the middle of the first area.
The second orc is located near the end of 2nd area.
The third one is located south west of the 3rd area.
The fourth one is located at the end of the 4th area.

Note: This enchanted orcs moves, but if you do it fast they should be around those areas.

After killing the last orc a portal to the next map will open.

Exploring the 2nd Area

To start the 2nd area talk again to Kruger.
He will explain to you that you need to strengthen the flame of the torches in each area and kill the guardian of each area to spawn the portal into the next area.
Only the party leader can do this.

[First Area]
[Second Area]
[Third Area]
    [Boss Area]

Finally the boss area
All you need to do is to kill the Orc Hero [Shaman Cargalache]
There are plenty of ways to kill this boss.
Though the easiest is probably sacrifice build by Royal Guards
If you need guide on how to kill using Royal Guards you can read the guide here.