D20:Ability Scores Rules

Each ability partially describes your character and affects some of his or her actions.
When an ability score changes, all attributes associated with that score change accordingly. A character does not retroactively get additional skill points for previous levels if she increases her intelligence.

Some creatures lack certain ability scores. These creatures do not have an ability score of 0?they lack the ability altogether. The modifier for a nonability is +0. Other effects of nonabilities are detailed in the ability descriptions.

• Strength
  
• Dexterity
  
• Constitution
  
• Intelligence
  
• Wisdom
  
• Charisma
  

The ability that governs bonus spells depends on what type of spellcaster your character is: Intelligence for wizards; Wisdom for clerics, druids, paladins, and rangers; or Charisma for sorcerers and bards. In addition to having a high ability score, a spellcaster must be of high enough class level to be able to cast spells of a given spell level. (See the class descriptions for details.)

The ability that your powers depend on?your key ability score as a manifester?is related to what psionic class (or classes) you have levels in: Intelligence (psion), Wisdom (psychic warrior), and Charisma (wilder). The modifier for this ability is referred to as your key ability modifier. If your character?s key ability score is 9 or lower, you can?t manifest powers from that psionic class.
Just as a high Intelligence score grants bonus spells to a wizard and a high Wisdom score grants bonus spells to a cleric, a character who manifests powers (psions, psychic warriors, and wilders) gains bonus power points according to his key ability score. Refer to Table: Ability Modifiers and Bonus Power Points.

Each ability, after changes made because of race, has a modifier ranging from ?5 to +5. Table: Ability Modifiers and Bonus Spells shows the modifier for each score. It also shows bonus spells, which you?ll need to know about if your character is a spellcaster.
The modifier is the number you apply to the die roll when your character tries to do something related to that ability. You also use the modifier with some numbers that aren?t die rolls. A positive modifier is called a bonus, and a negative modifier is called a penalty.

[top]Table: Ability Modifiers and Bonus Spells

Score	Modifier	Bonus Spells (by Spell Level)
		0	1st	2nd	3rd	4th	5th	6th	7th	8th	9th
1	?5	Can?t cast spells tied to this ability
2?3	?4
4?5	?3
6?7	?2
8?9	?1
10?11	0	?	?	?	?	?	?	?	?	?	?
12?13	+1	?	1	?	?	?	?	?	?	?	?
14?15	+2	?	1	1	?	?	?	?	?	?	?
16?17	+3	?	1	1	1	?	?	?	?	?	?
18?19	+4	?	1	1	1	1	?	?	?	?	?
20?21	+5	?	2	1	1	1	1	?	?	?	?
22?23	+6	?	2	2	1	1	1	1	?	?	?
24?25	+7	?	2	2	2	1	1	1	1	?	?
26?27	+8	?	2	2	2	2	1	1	1	1	?
28?29	+9	?	3	2	2	2	2	1	1	1	1
30?31	+10	?	3	3	2	2	2	2	1	1	1
32?33	+11	?	3	3	3	2	2	2	2	1	1
34?35	+12	?	3	3	3	3	2	2	2	2	1
36?37	+13	?	4	3	3	3	3	2	2	2	2
38?39	+14	?	4	4	3	3	3	3	2	2	2
40?41	+15	?	4	4	4	3	3	3	3	2	2
42?43	+16	?	4	4	4	4	3	3	3	3	2
44?45	+17	?	5	4	4	4	4	3	3	3	3
etc. . .

Your key ability score grants you additional power points equal to your key ability modifier × your manifester level ×1/2. Table: Ability Modifiers and Bonus Power Points shows these calculations for class levels 1st through 20th and key ability scores from 10 to 41.

[top]Table: Ability Modifiers and Bonus Power Points

Ability Score	Bonus Power Points (by Class Level)
	1st	2nd	3rd	4th	5th	6th	7th	8th	9th	10th	11th	12th	13th	14th	15th	16th	17th	18th	19th	20th
10?11	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
12?13	0	1	1	2	2	3	3	4	4	5	5	6	6	7	7	8	8	9	9	10
14?15	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
16?17	1	3	4	6	7	9	10	12	13	15	16	18	19	21	22	24	25	27	28	30
18?19	2	4	6	8	10	12	14	16	18	20	22	24	26	28	30	32	34	36	38	40
20?21	2	5	7	10	12	15	17	20	22	25	27	30	32	35	37	40	42	45	47	50
22?23	3	6	9	12	15	18	21	24	27	30	33	36	39	42	45	48	51	54	57	60
24?25	3	7	10	14	17	21	24	28	31	35	38	42	45	49	52	56	59	63	66	70
26?27	4	8	12	16	20	24	28	32	36	40	44	48	52	56	60	64	68	72	76	80
28?29	4	9	13	18	22	27	31	36	40	45	49	54	58	63	67	72	76	81	85	90
30?31	5	10	15	20	25	30	35	40	45	50	55	60	65	70	75	80	85	90	95	100
32?33	5	11	16	22	27	33	38	44	49	55	60	66	71	77	82	88	93	99	104	110
34?35	6	12	18	24	30	36	42	48	54	60	66	72	78	84	90	96	102	108	114	120
36?37	6	13	19	26	32	39	45	52	58	65	71	78	84	91	97	104	110	117	123	130
38?39	7	14	21	28	35	42	49	56	63	70	77	84	91	98	105	112	119	126	133	140
40?41	7	15	22	30	37	45	52	60	67	75	82	90	97	105	112	120	127	135	142	150

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