From Basin Wiki

Contents 1 Stacking Percentages 2 Casting Order 2.1 Casting Method 2.2 Equipped Order 2.3 Skill/Stat Order 2.4 Skill Level

Stacking Percentages

The % chance to cast of multiple modifiers of the same skill, level and casting method are stacked or summed e.g. a Treachery 'ShaelThulLem' armour's 25% Chance to Cast Level 15 Venom on Striking and a Grief 'EthTirLoMalRal' Phase Blade's 35% Chance to Cast Level 15 Venom on Striking share the same skill (Venom), level (15) and casting method (on Striking), resulting in a 60% (25 + 35) Chance to Cast Level 15 Venom on Striking. [1]

Note that % Chance to Cast on Attack, Striking and When You Kill an Enemy modifiers on weapons are restricted to that weapon e.g. a Barbarian wearing a Treachery armour with a Grief Phase Blade in each hand will have 60% Chance to Cast Level 15 Venom on Striking with each weapon, not 95% (25 + 35 + 35). [2]

Casting Order

The order in which multiple successful % Chance to Cast modifiers are cast is normally irrelevant; if two or more modifiers are triggered at once, all will be cast. [3] This is true even if two or more cast-delayed spells are cast; the delays are not applied and all will be cast, even during the casting delay of one of the player's own skills (conversely, they will not prevent the player's cast-delayed skills from being used). [4]

The only situations in which casting order becomes relevant are when two or more next-hit delayed skills are cast (since the next-hit delay of the first one cast may prevent those following it from affecting the target) or when two or more Curses are cast (since the last one cast will normally overwrite those preceding it).

While a Barbarian's Battle Cry and an Assassin's Cloak of Shadows are considered curses, neither can be cast by any % Chance to Cast modifiers. [5]

The factors affecting casting order for all remaining cases take precedence in the following order:

1. Casting Method
2. Equipped Order
3. Skill/Stat Order
4. Skill Level

Casting Method

Modifers with different casting methods are cast in the following order:

	Curses [6]		Spells [7]
Active
1.	On Striking	1.	On Attack
2.	On Attack	2.	On Striking
3.	When You Kill an Enemy	3.	When You Kill an Enemy
4.	When You Level-up	4.	When You Level-up
Passive
1.	When Struck	1.	When Struck
2.	When You Die	2.	When You Die

Note that % Chance to Cast When Struck modifiers won't be applied if the attack is blocked, dodged, avoided or evaded.

Equipped Order

Modifers with the same casting method will then be cast in the order in which the items they're on were equipped; first equipped, first cast and so on. [8] [9] Only when you switch weapons, level-up or you (or your hireling) die, will the game re-equip your weapons or items in the order specified in BodyLocs.txt: [10]

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

Modifiers with the same casting method on the same item will be cast in the order in which they are displayed; however, while curses are cast in descending order (first to last), [11] spells are cast in ascending order (last to first): [12]

	Curses		Spells
1.	Taunt	8.	Tornado
2.	Howl	7.	Volcano
3.	Lower Resist	6.	Twister
4.	Decrepify	5.	Poison Nova
5.	Attract	4.	Teeth
6.	Life Tap	3.	Chain Lightning
7.	Confuse	2.	Nova
8.	Terror	1.	Frost Nova
9.	Iron Maiden
10.	Weaken
11.	Dim Vision
12.	Amplify Damage
13.	Hit Blinds Target
14.	Hit Causes Monster to Flee

While most skills and curses on these lists will be cast and applied simultaneously, there are some exceptions due to the mechanics of individual skills: Howl may be cast second, but it is applied last; [13] and the nature of Twister, Volcano and Tornado will often result in variations between casting and application.

Skill Level

Modifiers with the same casting method, on the same item and of the same skill will be cast in ascending order of skill level i.e the lowest skill level is cast first and the highest is cast last. [14] Casting order for different levels of the same curse is irrelevant due to their mechanics: a lower level will not overwrite a higher one; equal levels will simply reset the length; and a higher level will overwrite a lower one. The only exceptions are Confuse, Attract and Howl, which cannot overwrite themselves.