Relic’s Key is the first dungeon introduced in Order and Chaos Online in the second major content update in August 2011. There are two versions of the dungeon; a regular level 35 and a level 60 ‘legendary’ one. It is set up as a ‘wave’ style dungeon with mobs and bosses coming at you over a series of waves. People may be familiar with this style from World of Warcraft. There are a total of three bosses that each come in after three to five waves of mobs.
Guide to Relic’s Key Dungeon – Terrific Dungeon Guide
Video Walkthrough of Relic’s Key Dungeon – Best I Could Find