Spell hindrance

Spell hindrance is a system that imparts a chance for heavier armors to prevent spells from being successfully cast.

Robes, light leather, and full leather armors allow spells from all circles to be cast with no hindrance. Reinforced leather and double leather cause hindrance for some elemental and mental spell circles. Characters wearing leather breastplate or heavier armor will incur at least some hindrance for spells cast from any spell circle.

Casters wearing heavier armors will experience a random chance of spell failure. A base mana cost will be taken, stance will be forced down from defensive, and the standard 3 second cast roundtime takes place, but there is no further effect:

You trace a sign while beseeching the spirits to empower you with the Bind spell...
Your spell is ready.
You gesture at a skeletal lord.
[Spell Hindrance for some marbled pink mithril armor is 9% with current Armor Use skill, d100= 7]
Your armor prevents the spell from working correctly.
Cast Roundtime 3 Seconds.
(Forcing stance down to guarded)

The percentage of chance is variable based on the type of spell and type of armor.

Reducing Hindrance

Each point of base hindrance is increased by (base hindrance / 20) per point of Armor Use bonus away from the required amount. Base hindrance is the minimum hindrance that can be attained with enough Armor Use (i.e., ((20 bonus * Base Hindrance) - 10).

Hindrance can be additionally reduced both by the spell Faith's Clarity (1603) and by the paladin's armor specialization Armored Fluidity.

Hindrance is entirely negated in natural sanctuaries and areas where Minor Sanctuary (213) is in effect.

Chart of Armor Penalties and Hindrance

AG	AsG	Name	RT	AP	Spell Hindrance
					MnS	MjS	Cleric	MnE	MjE	Ranger	Sorcerer	Wizard	Bard	Empath	Paladin	Max
Cloth	1	Robes	0	0	-	-	-	-	-	-	-	-	-	-	-	-
Soft Leather	5	Light leather	0	0	-	-	-	-	-	-	-	-	-	-	-	-
	6	Full leather	1	0	-	-	-	-	-	-	-	-	-	-	-	-
	7	Reinforced leather	2	-5	-	-	-	-	2	-	1	2	-	-	-	4
	8	Double leather	2	-6	-	-	-	-	4	-	2	4	2	-	-	6
Hard Leather	9	Leather breastplate	3	-7	3	4	4	4	6	3	5	6	3	4	2	16
	10	Cuirbouilli leather	4	-8	4	5	5	5	7	4	6	7	3	5	3	20
	11	Studded leather	5	-10	5	6	6	6	9	5	8	9	3	6	4	24
	12	Brigandine armor	6	-12	6	7	7	7	12	6	11	12	7	7	5	28
Chain	13	Chain mail	7	-13	7	8	8	8	16	7	16	16	8	8	6	40
	14	Double chain	8	-14	8	9	9	9	20	8	18	20	8	9	7	45
	15	Augmented chain	8	-16	9	11	11	10	25	9	22	25	8	11	8	55
	16	Chain hauberk	9	-18	11	14	14	12	30	11	26	30	15	14	9	60
Plate	17	Metal breastplate	9	-20	16	25	25	16	35	21	29	35	21	25	10	90
	18	Augmented plate	10	-25	17	28	28	18	40	24	33	40	21	28	11	92
	19	Half plate	11	-30	18	32	32	20	45	27	39	45	21	32	12	94
	20	Full plate	12	-35	20	45	45	22	50	30	48	50	50	45	13	96

Resources

• http://www.play.net/gs4/info/armory/armor.asp