Chance to Cast

Skills	% Chance to Cast	Charges	Oskills	Aura When Equipped

% Chance to Cast gives a chance to use a skill when triggered by an event, without costing any mana. Skill level cannot be increased: however, equipping multiple % Chance to Cast of the same skill, level and event will result in the individual percentages being added together to apply a single % Chance to Cast of that skill, level and event (although >100% Chance to Cast is redundant). [1] Skills used receive passive bonuses including synergy bonuses, but do not apply them. The existence of pets summoned will be unstable unless the player invests skill points in the native skill or acquires it from an Oskill. Pets will not be summoned by hirelings. % Chance to Cast on Attack, on Striking and When You Kill an Enemy are restricted to the weapon on which they spawn (% Chance to Cast on one weapon will not apply to the other). [2] No % Chance to Cast is applied while using Whirlwind. Ladder Unique items can be found in Ladder and single-player games; Ladder Rune Words can only be made in Ladder games.

Skill level

% Chance to Cast normally specifies a set skill level (slvl), but a few apply a skill level which is dependent on the skill's required level (rlvl) and the item level (ilvl): slvl = min([(ilvl-rlvl)/4]+1,20). [3] The table below specifies the minimum ilvl required for particular slvls, dependent on the skill's rlvl.

Rlvl	Slvl
	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
1	1	5	9	13	17	21	25	29	33	37	41	45	49	53	57	61	65	69	73	77
6	3	10	14	18	22	26	30	34	38	42	46	50	54	58	62	66	70	74	78	82
12	9	16	20	24	28	32	36	40	44	48	52	56	60	64	68	72	76	80	84	88
18	15	22	26	30	34	38	42	46	50	54	58	62	66	70	74	78	82	86	90	94
24	21	28	32	36	40	44	48	52	56	60	64	68	72	76	80	84	88	92	96
30	27	34	38	42	46	50	54	58	62	66	70	74	78	82	86	90	94	98

This only applies to seven Unique items. In practice, minimum slvl is determined by the Unique item level or its base item level, whichever is highest. The table below specifies the minimum ilvl required for particular slvls.

Unique item	Level		Skill	Rlvl	Slvl									Chance	Event
	Unique	Item			12	13	14	15	16	17	18	19	20
Template:D2 Unique	66	73	Chain Lightning	18			70	74	78	82	86	90	94	5	On Attack
Template:D2 Unique	71	73	Fire Ball	12					72	76	80	84	88	10	On Attack
Template:D2 Unique	49	42	Charged Bolt	1		49	53	57	61	65	69	73	77	10	On Striking
Template:D2 Unique	73	1	Meteor	24		72	76	80	84	88	92	96		2	When Struck
Template:D2 Unique	49	49	Blizzard	24		72	76	80	84	88	92	96		5	When Struck
Template:D2 Unique	50	46	Holy Bolt	6	50	54	58	62	66	70	74	78	82	50	When Struck
Template:D2 Unique	78	85	Charged Bolt	1									77	2	When Struck

On Attack

% Chance to Cast on Attack is applied whenever using a melee attack even when that attack misses or gets blocked, or if Dodge, Evade or Weapon Block are applied.

• Not applied when using a ranged attack or missile weapon (Amazon bow, bow or crossbow), except when a Werewolf or Werebear is using a missile weapon with a melee attack.
• Applied by Blade Shield (although it is applied as on Striking).
• Charged Bolt and Frozen Orb are cast at the target from the user's location; all other skills below are cast at or from the target's location.

Class	Skill	Level	Chance	Item	Ladder
Sorceress	Charged Bolt	20	20	Template:D2 Unique sword/hammer/axe	Yes
	Fire Ball	6	10	Template:D2 Unique	No
		16-20	10	Template:D2 Unique	No
	Nova	22	15	Template:D2 Unique polearm/sword	Yes
	Chain Lightning	14-20	5	Template:D2 Unique	No
	Glacial Spike	18	25	Template:D2 Unique sword/axe	Yes
	Frozen Orb	21	16	Template:D2 Unique polearm/scepter	Yes

Item suffixes

• All suffixes can spawn on magic, rare and crafted items.
• All suffixes are in the same affix group as on Striking, When Struck and charged suffixes.

Class	Skill	Level	Chance	Item	Alvl	Rlvl
Sorceress	Fire Bolt	3	5	Weapon 1	6	4
		4	10		20	15
	Ice Bolt	3	5	Weapon 1	6	4
	Lightning	3	5	Weapon 1	18	13
	Chain Lightning	3	5	Amulet Weapon 1 Ring	25	18
		3	8		35	26
		5	8		45	33

¹ Excluding missile weapons

On Striking

• On Striking

When Struck

• When Struck

When You Die

• Poison Nova and Nova are cast from the user's location.
• Chain Lightning is cast from the user's location at the killer.
• Meteor and Blizzard are cast on the killer's location.

Class	Skill	Level	Chance	Item	Ladder
Necromancer	Poison Nova	51	100	Template:D2 Unique	No
Sorceress	Nova	44	100	Template:D2 Unique	No
	Chain Lightning	44	100	Template:D2 Unique sword/axe	Yes
		47	100	Template:D2 Unique	No
	Meteor	31	100	Template:D2 Unique	No
		45	100	Template:D2 Unique polearm/sword	Yes
		48	100	Template:D2 Unique weapon	No
	Blizzard	37	100	Template:D2 Unique	No

When You Kill an Enemy

% Chance to Cast When You Kill an Enemy is applied when a target is killed by the user's weapon damage, poison damage applied by either weapon or skill, or Open Wounds.

• Decrepify and Chain Lightning are cast from the target's location.
• Poison Nova is cast from the user's location.
• Enchant is cast on the user only.

Class	Skill	Level	Chance	Item	Ladder
Necromancer	Decrepify	6	50	Template:D2 Unique	Yes
	Poison Nova	20	50	Template:D2 Unique weapon	No
Sorceress	Enchant	21	30	Template:D2 Unique polearm	Yes
	Chain Lightning	20	50	Template:D2 Unique polearm	Yes

When You Level-up

• All skills below are cast on the user, or on or from their location.

Class	Skill	Level	Chance	Item	Ladder
Assassin	Venom	23	100	Template:D2 Unique	No
Sorceress	Frost Nova	43	100	Template:D2 Unique	No
	Blaze	29	100	Template:D2 Unique	No
		36	100	Template:D2 Unique weapon	No
		40	100	Template:D2 Unique weapon/shield	Yes
	Nova	41	100	Template:D2 Unique	No
	Blizzard	40	100	Template:D2 Unique missile weapon	Yes

Casting order

Casting order is normally irrelevant: if two or more skills are triggered by the same event, all are cast, even if there are two or more delays: those for each skill are not applied. [4] [5] However, an 11 frame delay is applied from the action flag (the frame in the attack or casting animation in which the action is actually executed). During this delay no active skills can be used, although Scrolls of Identify and Town Portal placed in the belt can be used. [6] [7]

This 11 frame delay does not interrupt an attack sequence if % Chance to Cast is applied during that sequence. The delay can be applied from the action flag of any individual attack in the sequence, so if it is applied by an attack early in the sequence then the delay may end before that sequence ends. If multiple attacks in a sequence apply % Chance to Cast, the delay is applied from the last attack in the sequence to apply it. [8]

Casting order only becomes relevant when two or more skills using next delay missiles are cast (since the next delay of the first cast may prevent those following from applying to the target), or when two or more Curses are cast (since the last cast will normally overwrite those preceding it). The factors affecting casting order for all remaining cases take precedence in the following order:

Trigger event

Event	Curses [9]	Other [10]
Active	On Striking On Attack When You Kill An Enemy When You Level-up	On Attack On Striking When You Kill An Enemy When You Level-up
Passive	When Struck When You Die	When Struck When You Die

Equipping order

When the trigger event is the same, equipping order determines casting order: first equipped, first cast and so on. [11] [12] Only when the user switches weapons, levels-up or dies will the game re-equip weapons or items in the following order: [13]

1. Head
2. Neck
3. Torso
4. Right Arm
5. Left Arm
6. Right Ring
7. Left Ring
8. Belt
9. Feet
10. Gloves

Skill/stat order

When the trigger event and item are the same, casting order is determined by the displayed order: Curses are cast in descending order (first displayed to last), [14] while other skills are cast in ascending order (last displayed to first). [15] The table lists Curses and skills in casting order, not displayed order:

Curse	Skill
Taunt Howl 1 Lower Resist Decrepify Attract Life Tap Confuse Terror Iron Maiden Weaken Dim Vision Amplify Damage Hit Blinds Target Hit Causes Monster to Flee	Frost Nova Nova Chain Lightning Teeth Poison Nova Twister 2 Volcano 2 Tornado 2

¹ Howl may be cast second, but due to its mechanics it is actually applied last. [16]
² Twister, Volcano and Tornado mechanics will often result in variations between casting and application order.

Skill Level

When the trigger event, item and skill are the same, casting order is determined by ascending order of skill level: the lowest is cast first and the highest is cast last. [17]

References

• Adeyke, Random level of CTC skill (Technical Discussion)
• Onderduiker, % Chance to Cast and Curses Tests (Technical Discussion)