When Struck

% Chance to Cast When Struck is applied whenever the user is hit by a melee attack (excluding charging Claw Vipers and Reanimated Horde), a missile attack applying weapon or monster damage, persistent traps or fires, or exploding barrels.
Not applied by missiles which only apply their own damage or skill damage. Most of the applicable missile attacks are intuitive (the user is hit by a visible arrow, bolt, dart, javelin, quill or throwing weapon), but others are less obvious:
- Tainted lightning orbs
- Skeleton Mage bolts
- Lightning Spire bolts
- Willowisp lightning bolts
- Demon Imp fire bolts
- Claw Viper missiles
- Succubus and Stygian Fury bolts
Not applied by returned damage or death explosions.
Skills are cast in a variety of ways:

User	User Location	User to Attacker	Attacker Location
Fade Venom Cyclone Armor Bone Armor Blaze Enchant Teleport Chilling Armor Delerium	Slow Missiles Howl Poison Nova Static Field Frost Nova Nova	Twister Tornado Bone Spirit Holy Bolt Charged Bolt Chain Lightning Glacial Spike	Mind Blast Curses Bone Prison Fist of the Heavens Fire Wall Meteor Blizzard Hydra

Amazon skill

Template:D2 Chance |- !align=left|Slow Missiles |5 |4 |align=left|Peace body armor |29 |No |}

Assassin skill

Template:D2 Chance |-valign=top !align=left rowspan=3|Fade |8 |5 !align=left|Spirit Ward Ward |68 |No |- |11 |6 |align=left|Last Wish axe/hammer/sword |65 !Yes |- |15 |5 |align=left|Treachery body armor |43 |No |- !align=left|Mind Blast |14 |6 |align=left|Delirium helm |51 |No |- !align=left|Venom |18 |20 |align=left|Dragon body armor/shield |61 !Yes |}

Barbarian skill

Template:D2 Chance |- !align=left|Howl |1 |3 |align=left|Myth body armor |25 |No |}

Druid skill

Template:D2 Chance |- !align=left|Cyclone Armor |15 |5 |align=left|Rain body armor |49 |No |- !align=left|Twister |1 |7 |align=left|Zephyr missile weapon |21 |No |- !align=left|Tornado |5 |4 !align=left|Stormchaser Scutum |35 |No |}

Necromancer skill

Template:D2 Chance |- !align=left|Amplify Damage |14 |35 |align=left|Brand missile weapon |65 !Yes |- !align=left|Bone Armor |10 |15 |align=left|Bone body armor |47 |No |-valign=top !align=left rowspan=2|Dim Vision |3 |6 !align=left|Darksight Helm Basinet |38 |No |- |3 |15 |align=left|Gloom body armor |47 |No |- !align=left|Weaken |5 |4 !align=left|Blackoak Shield Luna |61 |No |-valign=top !align=left rowspan=4|Iron Maiden |1 |5 !align=left|The Gavel of Pain Martel de Fer |45 |No |- |2 |6 !align=left|Corpsemourn Ornate Plate |55 |No |- |2 |10 !align=left|Saracen's Chance Amulet |47 |No |- |6 |8 !align=left|Steel Carapace Shadow Plate |66 |No |-valign=top !align=left rowspan=2|Terror |3 |15 !align=left|Boneflame Succubus Skull |72 |No |- |13 |14 |align=left|Delirium helm |51 |No |- !align=left|Confuse |15 |10 |align=left|Dream helm/shield |65 !Yes |- !align=left|Bone Prison |2 |10 !align=left|Arm of King Leoric Tomb Wand |36 |No |- !align=left|Lower Resist |7 |10 !align=left|Medusa's Gaze Aegis |76 |No |-valign=top !align=left rowspan=4|Poison Nova |5 |5 !align=left|Radament's Sphere Ancient Shield |50 |No |- |6 |9 !align=left|Pus Spitter Seige Crossbow |36 |No |- |10 |10 !align=left|Carrion Wind Ring |60 |No |- |15 |15 !align=left|Andariel's Visage Demonhead |83 !Yes |- !align=left|Bone Spirit |10 |5 !align=left|Arm of King Leoric Tomb Wand |36 |No |}

Paladin skill

Template:D2 Chance |- !align=left|Holy Bolt |(12-20) |50 !align=left|Boneslayer Blade Gothic Axe |42 |No |- !align=left|Fist of the Heavens |7 |5 !align=left|Thundergod's Vigor War Belt |47 |No |}

Sorceress skill

Template:D2 Chance |-valign=top !align=left rowspan=4|Charged Bolt |3 |25 !align=left|Stormspike Stilleto |41 |No |- |4 |12 !align=left|Immortal King's Forge War Gauntlets |30 |No |- |20 |2 !align=left|Stormspire Giant Thresher |70 |No |- |5 |15 !align=left|Stormrider Tabar |41 |No |-valign=top !align=left rowspan=2|Static Field |3 |10 !align=left|Hwanin's Refuge Tigulated Mail |30 |No |- |5 |25 |align=left|Cow King's Leathers (Full) |25 |No |-valign=top !align=left rowspan=3|Frost Nova |4 |5 |align=left|Hit Power item |13 |No |- |5 |10 !align=left|Coldkill Hatchet |36 |No |- |9 |5 !align=left|Tiamat's Rebuke Dragon Shield |38 |No |-valign=top !align=left rowspan=2|Blaze |8 |5 !align=left|Infernostride Demonhide Boots |29 |No |- |15 |5 |align=left|Enlightenment body armor |45 |No |-valign=top !align=left rowspan=2|Nova |3 |25 !align=left|Dark Adherent Dusk Shroud |49 |No |- |7 |5 !align=left|Tiamat's Rebuke Dragon Shield |38 |No |- !align=left|Fire Wall |17 |25 |align=left|Pride polearm |67 !Yes |- !align=left|Enchant |5 |5 !align=left|Immortal King's Soul Cage Sacred Armor |76 |No |-valign=top !align=left rowspan=3|Chain Lightning |5 |5 !align=left|Stormspire Giant Thresher |70 |No |- |5 |12 !align=left|Naj's Circlet Circlet |28 |No |- |5 |18 !align=left|Cow King's Hide Studded Leather |18 |No |- !align=left|Teleport |1 |25 !align=left|The Oculus Swirling Crystal |42||No |- !align=left|Glacial Spike |3 |10 !align=left|M'avina's Embrace Kraken Shell |70 |No |- !align=left|Meteor |(13-19) |2 !align=left|The Rising Sun Amulet |65 |No |-valign=top !align=left rowspan=2|Blizzard |6 |4 !align=left|Stormchaser Scutum |35 |No |- |(7-19) |5 !align=left|Snowclash Battle Belt |42 |No |- !align=left|Chilling Armor |15 |20 |align=left|Fortitude body armor/weapon |59 !Yes |- !align=left|Hydra |6 |3 !align=left|Tiamat's Rebuke Dragon Shield |38 |No |}

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

Skill	Level	% Chance	Item	Min Rlvl	Min Alvl
Charged Bolt	3	10	Armor Amulet Ring	4	6
	4	12		12	16
	5	14		19	26
Frost Nova	3	5	Armor Amulet	9	12
Nova	3	10	Armor Ring	13	18
	4	12		21	28
	5	14		28	38
Hydra	3	10	Amulet	30	40

Other skill

Template:D2 Chance |- !align=left|Delerium |50 |1 |align=left|Delirium helm |51 |No |}

Reference

Onderduiker, Chance to Cast and Curses Tests (Technical Discussion)