Outer Wall of Serdin is the third dungeon on the continent of Bermesiah and is the third one encountered in the game. It is also the first dungeon in Champion Mode.
Just as the trio, Elesis, Arme, and Lire, finished Trial Tower, the Orcs have begun their siege on Serdin. They decide to head out and repel the attack. Sieghart is encountered here, whom is looking for a group called "Grand Chase". Elesis gets enraged because he and her both bear the same last name. Sieghart then leaves afterward, without knowing the three girls were members of the guild, and requests them to tell the Chase to meet him in Xenia Continent. As they reach one section, they find the leader, a massive Orc Warrior. He is, of course, slain as well. In the aftermath, Elesis reveals to be from the House of Sieghart and leads a group called the Ruby Knights.
Orc Warrior appears first as the boss of the Outer Wall of Serdin and later as a normal enemy. However, in Season 2, the boss version of Orc Warrior wears a helmet unlike the Orc Warriors found as normal monsters. In Season 3, Orc Warriors as normal monsters have a helmet as well. Two versions of the Orc Warrior are the Orc Zombie Warrior and the Violent Orc Warrior. There is also another Orc Warrior in the Bloodwind Clan.
The Orc Warrior's attacks consist of a run where he bucks his head and charges into players, a spin attack, and an earthquake that players must jump to avoid or they will take damage. The version of Orc Warrior found as a normal monster does not use the running attack perhaps because of the loss of the helmet. He can be a tough boss to newer players.
For newer players, note that there is a Jump Warning. This means the boss will use an attack that usually causes an earthquake with indefinite range. As the name implies, Jump!