You can find skeleton warriors on \join graveyard /join swordhavenundead /join battleunderb
/join graveyard /join battleundera /join battleunderb /join battleunderc /join swordhavenundead
complete the girl's quests in battleunderb until you reach the final quest, which is opening the portal. to open the portal, a shadowy shape will appear on some sort of rune thingy, and it will disappear quickly. you have to draw a line on where the shadowy shape was from one end to another, and dont let a single part of the line get out of the shape.
To begin the "Understanding Undead Champions" quest in AdventureQuest Worlds, you need to speak to Artix in the Battleon town square. He will give you the quest that involves battling undead monsters in different locations to prove your understanding of their ways.
You can find limestones in AQWorlds by defeating monsters or completing quests in various areas of the game. Some specific locations where you can find limestones include /join bludrutbrawl, /join swordhaven, and /join battleunderb. Keep battling monsters and completing quests in these areas to collect the limestones you need.