The Purge Meter fills as players perform various activities in the game. When it reaches the first mark at roughly 75% of the bar there is a chance for the Purge to occur. The bar will continue to fill from 75% to 100%, acting as a buffer to trigger the next purge. Clans share the same Purge Meter. Once eligible, a Purge has a chance to occur at any time.
On official servers' purges will only trigger during "Purge Time" which is a subset of prime time, "Purge Time" is between 6 PM and 10 PM local time (18:00 - 22:00), all days.
If you open up your inventory, you'll see a bar beneath your character. This is the Purge Meter. As you play the game (gather resources, build, kill NPCs, explore the world), it will start to fill up. Once it reaches the first line you can be attacked by a Purge. It won't happen automatically when you go over the threshold, but as long as your Purge activity score is above it, there's a chance for it to happen. Keep in mind that it's always a chance, not a guarantee.
The system works on a periodic scoring system. If anyone in a clan performs an action in that period - e.g. kill a player, build something etc., then that event is added to the list of events that have been performed in that period. The amount of times an action is performed and the amount of players that perform it, is irrelevant. A clan that kills 1 NPC will receive the same score as a clan that kills 1000. Every update cycle, the Purge events are added together and the score is added to the Purge meter. All Purge events are then cleared for the start of the next period.
The following activities performed by players fill the Purge Meter:
- Log On (100)
- Respawning from death counts as logging in.
- Timer Tick 60 minutes (62.5)
- This still gives points every 15 minutes.
- Kill another player (200)
- Kills using a Battle Standard on a PvE server does count.
- Killing someone via Tower of the Elephant does not count.
- Kill an NPC (200)
- Any non-player enemy, humanoid or creature, counts.
- Kills made by your follower do not count.
- Place T1 (200)
- Place T2 (200)
- Place T3 (200)
- Must be placed by itself; cannot be attached to any other pre-existing structure. This means only foundations or pillars can work.
- Separate tiers do not stack; you can only get points from placing a piece from one of the three tiers at a time.
Also possible activities, but currently not used:
- Craft Item
- Convert T1 Thrall
- Convert T2 Thrall
- Convert T3 Thrall
- Convert T4 Thrall
- Fill Purge Meter
- Drain Purge Meter
The Purge Meter Trigger Value in the Server Settings shows how many points are needed to trigger The Purge. (42,000 as standard)
The Purge Meter Update Interval is used such that during that interval, 1 kill grants the same number of points as do 100 kills.
The Purge Meter Update Interval refreshes by default every 15 minutes unless changed by a server admin.
In order to actually trigger a purge, a base needs to meet a few conditions :
- It needs to actually use foundations in its structure (this in turn allows for the design of "purge-free" bases that are built using for example only pillars and ceiling as floors)
- Enough foundations must be used. It is unclear whether only the amount of foundations and/or their quality (as in e.g. above T2 or T3 material) is involved into a base being eligible for purges. Streamer wak4863 states that a purge can't be triggered without at least 92 foundations being used in a base.
- Funcom added a purge meter decrease when players are offline multiple days. This was to try and get purges to activate on current active clans instead of triggering on inactive clans in the server database which had full purge meters but no buildings left on the server to target.
- Through Server Settings the time period in which Purges spawn can be limited (e.g. between 18:00 and 22:00 server time).
- Through Admin commands the Purge can be a.o. forced to take place.