What this covers: the vocabulary a Path of Exile 2, Diablo IV, Last Epoch or Grim Dawn build guide assumes — DPS versus effective DPS, EHP and its mitigation layers, damage conversion, ailment and damage-over-time scaling, cooldown recovery and the “CoC” conventions, and the breakpoints behind both. Why it matters: a guide is only as readable as its shorthand. Knowing that “increased” and “more” are different multipliers, or that your tooltip DPS is not the number a boss takes, turns a wall of abbreviations into a plan you can follow. Who should care: anyone opening a build-planner export or a league-start guide for the first time, and anyone comparing how four ARPGs describe the same underlying idea.
Every ARPGARPG. Action RPG — an RPG with real-time combat rather than turn-based fights. guide is written in a private language. A Path of Exile 2 guide says “10% increased” where a Grim Dawn guide says “10% percent damage”; all four mean something specific about how a number is multiplied. The vocabulary below is the set of terms that guides use without explaining, defined so that one article can be read in the context of another. Where the games genuinely differ, the difference is the point.
The vocabulary at a glance
| Term | Plain meaning | Where you meet it |
|---|---|---|
| DPS | damage per second the skill applies | the first number in any guide’s “damage” line |
| Effective DPS | DPS after crit chance, resistance, uptime and ramp | “single-target boss DPS” |
| Hit | one discrete application of damage | “on hit”, “hits and ailments” |
| DoT | damage applied repeatedly over a duration | bleed, poison, ignite |
| Conversion | turning one damage type into another | “physical converted to cold” |
| Mitigation | lowering the damage a hit deals to you | armour, resistances |
| Avoidance | making a hit not land at all | evasion, block, dodge |
| EHP | the pool plus every mitigation and avoidance layer | “how big a slam can I eat” |
| Breakpoint | a value where the next step only pays off past a threshold | attack speed for triggered casts |
| CoC | “cast on critical” — a trigger support | a spell firing itself off a crit attack |
DPS, and the arithmetic behind it
DPS is damage divided by time, but the arithmetic that produces it has a quirk that trips up new readers: in Path of Exile, all increased and reduced modifiers are additive with each other, while more and less modifiers are multiplicative. A passive that grants “10% increased damage” and another “20% increased damage” give 30% together; two “10% more damage” modifiers give 21%. That distinction is why two guides can quote the same passive and arrive at different final numbers — and why any guide worth reading states which word it means. The same page that documents the order of a damage calculation puts critical strike after global modifiers, where a hit “can be rolled as a critical strike which multiplies the damage by 150% by default” (PoEDB — Receiving damage). Diablo IV writes the identical idea two different ways in one tooltip: bonuses with a [+] are additive while those with [x] are “multiplicative,” and a critical strike “is multiplied by x1.5” (Maxroll — Damage for Beginners).
A skill’s tooltip DPS is therefore a lower bound, not an answer. The number usually hides four multipliers: your critical strike chance and multiplier, the enemy’s resistance and your penetration, your uptime (how much of the fight the skill is actually firing), and any ramp the skill needs before it reaches its stated damage. Guides quote “effective DPS” — sometimes “real DPS” or “boss DPS” — for the product of all four, and it is nearly always lower than the tooltip. Diablo IV makes the same warning explicit: the character sheet shows “an approximation of your DPS called Attack Power,” but “you shouldn’t rely on this number except as a very rough guideline. It doesn’t include a lot of damage bonuses… It also doesn’t include any debuffs you can have on monsters” (Maxroll — Damage for Beginners). When a guide says a build “does 30M DPS on Uber” and a comment disputes it, the argument is almost never about one number; it is about which of these multipliers the author counted.
EHP: the pool plus the multipliers
EHP, or effective health, is not your life bar. As a Path of Exile mechanics reference puts it, it is “how much raw incoming damage you can absorb before dying, once every defensive layer is accounted for — not just your Life bar.” The usable form is a pool multiplied by an avoidance factor and divided by the fraction of a hit that lands. A character with a 3,000 pool and 50% mitigation has roughly a 6,000 effective pool against that hit.
The important consequence is that EHP is measured against a specific hit, because mitigation is not a flat percentage. Path of Exile armour reduces a physical hit by Armour ÷ (Armour + 5 × Raw Damage), which means it is strong against many small hits and weak against one large one; the same math gives the “rule of thumb” that armour equal to five times the incoming damage halves that hit (PoE Wiki — Armour calculations). The multiplier itself is the defense factor, Armour ÷ (5 × Raw Damage) + 1 — the same idea EHP is built on. Path of Exile 2 uses a steeper curve, reducing a hit by Armour ÷ (Armour + 10 × hit), capped at 90%, which is why Path of Exile 2 armour stacking protects far better against crowds than against a single slam (poe2ref, a Path of Exile 2 mechanics reference). In Path of Exile 1, physical damage reduction from all sources is capped at 90%, and elemental and chaos damage is mitigated by its respective resistance, normally capped at 75% though items and passives can raise the maximum (PoEDB — Damage).
The same “pool plus layers” shape recurs across the genre, but the layers are named and capped differently.
| Game | Mitigation layers and caps | Avoidance | DoT interaction |
|---|---|---|---|
| Path of Exile 1 / 2 | armour (physical hits), resistances; physical reduction and resistances capped | evasion, block, dodge, spell suppression | DoT ignores evasion, shifts and armour; only broad reductions apply |
| Last Epoch | armour, resistances; block mitigation capped at 85%, dodge chance capped at 85% | block rolls on every hit including spells; dodge is all-or-nothing per hit | DoT cannot be dodged or blocked, and only resistances apply |
| Grim Dawn | resistances, then armour, then absorption; armour is location-based | fumble, dodge, projectile deflection, shield block via chance-to-hit | DoT is a separate stack source and is not life steal |
| Diablo IV | Life, Barrier, Fortify, armour, resistances and a separate multiplicative Damage Reduction stat; armour contributes half its value to non-physical damage | dodge; Resolve and Weaken modify incoming damage | DoT “cannot Critically Strike” |
The Last Epoch entries are documented directly: block “cannot protect you from Damage over Time effects” while dodging “does not count as being hit,” and both the block percentage and dodge chance are hard-capped at 85% (Last Epoch Support — Block; Last Epoch Support — Dodge). A useful rule of thumb from the same source: “having dodge rating equal to 10 times the area level will give you about 50% Dodge Chance.” The Diablo IV row comes from a defense guide whose layers are enumerated as Life, Barrier, Damage Reduction, Armor, Resistances, Toughness, Fortify, Dodge, Resolve and Weaken (Maxroll — In-depth Defense Guide), with the damage taken then multiplying through those layers in sequence: after armour and resistances, “the Damage Reduction kicks in to further reduce the incoming hit” (Diablo4.gg — Defenses Explained).
Grim Dawn instead makes armour a per-slot roll: a physical hit is assigned to a random body area, with the torso taking 26% of hits and legs 20%, and “whenever you take a physical damage hit, your armor will absorb some of the damage, up to the percentage of your armor absorption, but anything above your armor goes completely through” — so even a 124-point helmet against a 100-damage hit still lets a share through, because “30% of the damage will always go through because of armor absorption” (Grim Dawn — Combat).
Conversion, and why a guide cares
Conversion turns one damage type into another, and it changes which modifiers apply. In Path of Exile, “damage conversions do not apply to damage over time,” and conversion “applies early in a hit’s damage calculation: after added damage is added to base damage, but before multiplication by modifiers.” It follows a fixed order — Physical → Lightning → Cold → Fire → Chaos — and “steps can be skipped, but damage can never be converted backwards.” If conversion exceeds 100%, the modifiers “will be scaled down so that the total is 100%,” with skill conversion taking precedence over gear and passives. Converted damage “remembers the history of the damage types it was converted through,” so a lightning-to-cold conversion benefits from increases to lightning or cold or elemental damage, but only once (PoE Wiki — Damage conversion). Those two rules — order and multiplier inheritance — are the reason a converted-damage build scales the way it does.
Path of Exile 2 states the same ordering more briefly: “Conversion is a two step process. Conversion inherent to Skills occurs first, then Conversion from all other sources. Damage over time cannot be converted” (PoE2DB — Damage Conversion). Grim Dawn splits conversion into skill and global and applies it in a fixed chain — “Base Skill > Skill Modifiers > Conversion on Modifiers or Transmuter > Global Conversion on Equipment and Buffs > % damage on Equipment” — and, critically, “no matter where the Conversion occurs, it is only applied once,” so you cannot chain a transmuted skill through a second global conversion (Grim Dawn — Combat).
Ailments and damage-over-time scaling
Damage over time is where guides are most often read and least often explained. The cleanest rule is the one Last Epoch states outright: “Damage over time cannot be mitigated by most defense mechanics, except for resistances. Damage over time cannot critically strike and does not trigger on hit effects” (Last Epoch Support — Hit vs Damage over Time). Path of Exile’s page agrees in mechanism — “this damage source doesn’t hit which means that it ignores evasion, damage shifts, armour and other mechanics that requires a hit” — and adds the scaling rule most new players miss: modifiers to attack damage and spell damage do not contribute to ailment damage, and “modifiers to damage with weapons, melee damage, projectile damage and area damage do not apply to ailments under any circumstances” (PoEDB — Ailment). Ailments scale from the base damage of the skill that applies them, through ailment-specific and damage-over-time modifiers. Diablo IV’s damage guide draws the same line at the critical strike: “Only direct damage can Critically Strike, Damage over Time cannot” (Maxroll — Damage for Beginners).
Last Epoch’s ailment chance works as a stacking budget rather than a binary roll: “having an ailment chance greater than 100% allows you to apply multiple stacks at once if that ailment can stack. For example, if you have 235% ignite chance with Fireball, each Fireball hit will apply 2 stacks of ignite, with a 35% chance to apply a 3rd stack of ignite” (Last Epoch Support — Ailment Mechanics). Its damage is inherited from the applying skill: “affected by damage modifiers from the skill tree and attribute scaling of the skill that applies it,” and even an ailment applied by a melee hit does not count as melee damage.
Path of Exile’s damaging and non-damaging ailment values are a useful reference table, because guides quote them constantly:
| Ailment | Based on | Effect |
|---|---|---|
| Bleeding | physical attack damage | 70% of the hit as physical over 5s; moving targets take an extra 140% |
| Poison | physical and chaos damage | 30% of the combined hit as chaos over 2s; stacks independently |
| Ignite | fire damage | 125% of the fire hit as fire over 4s |
| Chill | cold damage | up to 30% slower actions, base 2s |
| Freeze | cold damage | zero action speed, 0.3s to 3s by default |
| Shock | lightning damage | up to 50% increased damage taken, base 2s |
| Scorch | fire damage | up to −30% elemental resistance, base 4s |
| Brittle | cold damage | up to +15% base critical strike chance against the target, base 4s |
| Sap | lightning damage | up to 20% less damage dealt, base 4s |
The source also notes that the critical-strike multiplier for ailments is a separate stat from the hit multiplier, with a base of 150% (PoEDB — Ailment). Grim Dawn handles the same territory with a stacking rule: “Unlike debuff effects, DoTs stack from different sources and always do full damage,” so a weapon poison and a spell poison both apply in full (Grim Dawn — Combat).
Cooldown recovery, CoC and breakpoints
The last cluster of shorthand is about time. Cooldown recovery rate does not subtract from a cooldown; it divides it, so a 50% increase on a 6-second cooldown yields 4 seconds (6 ÷ 1.5), not 3. In Path of Exile this creates hard breakpoints because the server resolves time in discrete frames, and “additional cooldown reduction that does not reach the next threshold is wasted.”
The classic case is CoC — Cast on Critical Strike — where a crit with a linked attack triggers a linked spell. The support carries a 150 ms cooldown, and cooldown recovery moves it in steps:
| Cooldown rate | Effective cooldown | Attack rate ceiling |
|---|---|---|
| 0% | 165 ms | 6.06 attacks per second |
| 14%+ | 132 ms | 7.57 |
| 52%+ | 99 ms | 10.10 |
| 128%+ | 66 ms | 15.15 |
Those attack rates are maximums, and exceeding them “even slightly can significantly reduce proc rate due to skipping procs while the skill is still on cooldown” — which is why CoC guides spend so long telling you to sit just under a number (PoE Wiki — Cast On Critical Strike). Two more trigger conventions matter: “Only one supported skill will be cast per trigger,” and which one fires “is determined based on the order in which it is socketed,” cycling through supported spells in sequence. Cooldowns are tracked per triggered skill, not per support, so you can fire different spells within the same window (PoEDB — Trigger). Breakpoints are not a Path of Exile peculiarity; any guide that says “reach 7.57 APS or don’t bother” is describing the same discrete-time interaction.
The shorthand guides assume
A few abbreviations recur. “MoM” is Mind over Matter, where a percentage of damage arriving at life “is removed from mana” (PoEDB — Receiving damage). “CI” is Chaos Inoculation, leaning on the rule that “chaos damage always bypasses energy shield” by making the pool entirely energy shield. “EHP” and “DPS” are the two headline figures; “GMP” and “AoE” are greater multiple projectiles and area of effect; “SSF” is solo self-found. In Last Epoch, “ward” is the energy-shield analogue that decays over time and is taken before health; in Grim Dawn, “OA” and “DA” are offensive and defensive ability, which resolve into one probability-to-hit whose thresholds decide both hit chance and critical tiers (Grim Dawn — Combat). In Diablo IV, “Barrier” and “Fortify” are the pool and reduction layers you will see named on gear. None of these are hard; they are simply never defined in the guide that uses them, which is the problem this glossary exists to fix.
If you want the loop these numbers are tuned against, the differences between endgame structures are covered in how Path of Exile 2, Last Epoch and Diablo IV endgame loops compare, and the craft systems that let you hit these thresholds are broken down in the build-crafting comparison.