1. Treasure chests – have only resources (gold, silver, gems, etc).
2. Chaos chests – have artifacts (weapon, armor, etc).
3. Crafted weapon and Artifacts.
Artifact can’t be more powerfull than best crafted weapon on the server. (For balancing craft and pve weapons)
But, some artifacts can have curse. Curse is debuff, that downgrade some stats, but also raise another. So, for example, there are can be weapons, that have +10 damage and -10 armor.
4. More deeper player opens chaos chest, more powerfull chaos npc spawns on the city, but also it have more powerfull artifact. E.g. on the 10 floor, spawns 6 lvl chaos npc, on the 30 – 26 lvl chaos npc. (This can be balanced)
This means that player choose between artifact and safety of the citizens. And player can have problems from another players, for spawning very powerfull chaos npc.