The main page on magic showed a number of ways in which a character can gain corruption points (CP). This page expands a bit on the effects of corruption. Not all of those are of the "your arm becomes a tentacle and all your hair falls out" variety; in fact, sometimes the effects can even be beneficial.

Whenever a character gains one or more CP, add them to the running total. Then check what happens. There are three possibilities:

1. If the character has fewer than ten CP, nothing happens

2. If the character has ten or more CP, but not more than his WP score, he makes a WP test. If he succeeds, nothing happens for now. However, if the test is failed, the character gains a corruption. Roll on the Corruption Table below. As corruption taints his body, though, the character loses 1d10 CP.

3. If the character gains more CP than his WP score, nothing can help him anymore; he is lost to Chaos. The character becomes an NPC in service of the Chaos Gods.


The Corruption Table

Roll 1d100 and add your Corruption Point total. Check the result on the following table, and click on the entry to see a further explanation.
00-20: Beneficial skill or talent
Yes, some mutations are actually beneficial. For instance, Wuder Lechart (in Grapes of Wrath) gained talents like Very Resilient and Very Strong. It is rare for something like this to happen, though - the character may praise himself lucky. Roll 1d100:

Magic skills and talents
01-04 Magical Sense (Witchsight)
05-08: Speak Language: Dark Tongue
09-12: Aethyric Attunement
13-16: Dark Lore
17-20: Dark Magic

Observation talents
21-24: Acute Hearing
25-28: Excellent Vision
29-32: Night Vision
33-36: Sixth Sense

Stat boosters
37-40: Coolheaded
41-44: Fleet Footed
45-48: Hardy
49-52: Lightning Reflexes
53-56: Marksman
57-60: Savvy
61-64: Suave
65-68: Very Resilient
69-72: Very Strong
73-76: Warrior Born

Others
77-80: Ambidextrous
81-84: Contortionist
85-88: Fearless (you know that you're doomed anyway)
89-92: Luck
93-94: Resistance to Disease
95-96: Resistance to Poison
97-00: Strike Mighty Blow
21-70: Arcane Mark
if a wizard, or a witch with a familiar, check the appropriate table. If not, pick a similar effect.
71-120: Minor Mutation
These are similar to the Side Effects described in the rulebook, on pages 159 and 160 (except for Mutation) or on the Disability Tables on pages 138 and 139 in the Version 1 rulebook. The first time the character rolls a Minor Mutation, roll on the tables to determine one. The character gets the first stage of this mutation. Next time, the character has a 90% chance of aggravating this mutation, and 10% to get a new minor mutation instead.
121 and more: Major Mutation
This is the squeaky stuff; tentacle arms, horns spouting from the forehead, and so on. Use the table on p. 229 of the rulebook, or another mutation table of your choice.