Chambers of Xeric is a points raid. Everything you do inside adds personal points, and your personal points at the end decide your chance at a unique. Understanding the formula changes how you play it.

Get there with ::cox or ::raids.

The purple chance formula

This is the whole raid in one line:

purple chance % = personal points / 1800

So 1,800 points is 1%. Nothing else about the raid matters for your unique chance except your own points total and the two multipliers below.

Personal points	Purple chance
18,000	10%
36,000	20%
54,000	30%
72,000	40%
81,000	45%, the cap

Purple chance is hard capped at 45%. Points beyond 81,000 do nothing for your unique chance, so there is no reason to grind a single raid past that unless you are chasing something else.

Personal points themselves cap at 130,000.

The two multipliers

Both only apply once you are above 1,000 points. Below that they are ignored entirely.

Raid Unique Charm

An equipment perk attached to a ring through item breakdown. It multiplies your purple chance by 5% per perk level.

Perk level	Multiplier
1	1.05x
2	1.10x
3	1.15x
4	1.20x
5	1.25x

At level 5 this is a flat quarter more purples for as long as you wear the ring. It is the single best investment for anyone raiding seriously. The ring must be equipped when the raid ends, not just owned.

Raiding Restorations

A perk tree perk. It also multiplies purple chance, scaling with its level. It stacks with the Raid Unique Charm rather than overlapping.

Running both, the 45% cap is reached at a lower point total than 81,000, which means shorter raids for the same chance.

Dying

Dying inside the raid costs you a percentage of your personal points. Supporter rank reduces it.

Rank	Points lost on death
No rank, Bronze, Iron	40%
Gold Supporter, Mithril Supporter	30%
Adamant Supporter	20%
Rune Supporter and above	10%

At 40% a single death near the end of a raid can cost you more than an entire room earned. Playing safely is worth more than pushing damage.

How to actually raid it

Points are personal, not shared. Your contribution is what counts, so do not idle and expect the team to carry your reward.
Do not die. The 40% penalty is the largest single swing in the raid for most players.
Get Raid Unique Charm on a ring. A flat 25% more purples at level 5 outweighs almost anything else you can change.
Stop at the cap. Once you are past 81,000 personal points, finishing the raid is worth more than farming more points.

Point sources

Points come from damage dealt, resources gathered and puzzle rooms completed. Damage on the bosses is the largest single contributor, which is why gear and a good perk setup matter more here than in most content.

Camel statue

When the Double Raid Points camel statue reward is active, all raid points earned are doubled. That halves the time to reach the 45% cap, so it is worth planning raids around.

Related

Item Breakdown and Equipment Perks for attaching Raid Unique Charm to a ring
Perks for Raiding Restorations, which is also part of the Gold Digger perk set
Donator Benefits for the full supporter rank table