City Tools Game math explained

Build Advice uses several bits of City of Heroes math that the game itself never spells out on screen. This page explains each one in plain language, with a real worked example, so a term in your advice is one click from a real answer instead of a guess. Every number on this page comes from this tool's own game-data files, or from direct in-game verification where the data files don't reach.

1. Rule of Five

Inside your build, one specific set bonus - e.g. the one printed as "10% Recharge Time" - only ever counts toward your totals up to five times, no matter how many powers, or even how many different sets, hand it to you. A sixth copy adds nothing: 0% extra effect, wherever it came from.

Two details the game never spells out. The count belongs to the bonus the game hands you, not to the words it prints: two different bonuses can print the same line, and each gets its own five. And five is not the only limit: some bonuses count once per build instead - Shield Wall's +Res(All), Preventive Medicine and Unbreakable Guard are three of them. How a bonus reaches you does not settle which kind it is: plenty of the bonuses handed to you by a single piece keep the usual five, among them Luck of the Gambler: Recharge Speed, Winter's Gift and Karma: Knockback Protection. So the limit is worth looking up rather than assuming - the Build Helper shows every bonus in a pasted build beside its own limit.

This is why "how many sets you're running" isn't the number that matters here - it's how many of them hand you the same bonus. The note under the Build tab's Slotted sets is telling you exactly this: which bonuses your build has already taken past their limit, and by how many copies.

Source: this tool's own set-bonus totals, which count each bonus up to the number of copies the game counts - five for most of them, once for the 26 that the game limits to a single copy per build - taking each bonus's own limit from the mined set-bonus data from the game's own data files.

2. Set bonuses & piece tiers

An enhancement set is a themed group of pieces you slot into one power. Slotting multiple pieces of the same set grants extra stat bonuses on top of whatever each individual piece already does on its own - and those bonuses unlock in tiers as you add more pieces, typically at 2, 3, 4, 5, and 6 pieces slotted. Every tier you reach stacks with the ones before it; a 6-piece set gives you the 2-piece bonus and the 3-piece bonus and every tier in between, all at once.

Source: this tool's own set-bonus totals (piece tiers 2 through 6, cumulative), checked against Hecatomb's own tier table in the mined set-bonus data from the game's own data files.

3. Typed vs. positional defense/resistance

Every attack in the game carries two separate labels: a damage type (Smashing, Lethal, Fire, Cold, Energy, Negative Energy, Toxic, or Psionic) and a position - roughly, how it's delivered (Melee, Ranged, or AoE). Your character tracks a separate Defense number and a separate Resistance number for each of the eight types and each of the three positions - eleven numbers apiece, and a set bonus can add to either kind depending on its wording.

The part that trips people up: when an attack lands, the game checks both of your matching numbers - the type's and the position's - but only uses whichever one is higher. They never add together.

This is why the Build tab shows two separate tables - one by damage type, one by position (Melee/Ranged/AoE): they're genuinely two different pools, and which one is actually protecting you against a given attack depends on which of the two you're stronger in.

Source: this tool's own typed/positional split, the same one that drives the Build tab's two coverage tables, for what it tracks; the "higher of the two, never both" combination rule is core, unpatched City of Heroes defense mechanics, confirmed against the Homecoming forums ("Positional vs Typed Defense" - forums.homecomingservers.com) and the community wiki's Defense article (cityofheroes.fandom.com/wiki/Defense).

4. Procs

A proc is an enhancement piece that, instead of (or alongside) boosting the power it's slotted into, has a chance to fire an extra effect of its own - almost always bonus damage - every time you use that power. The game's own combat log names these explicitly: a line reading <Set>: Chance for <Type> Damage (for example, "Apocalypse: Chance for Negative Energy Damage") is a proc firing, not the power's normal hit.

This tool treats a proc's damage as a rider, never as "your attack" - it's never counted toward a power's "best attack" ranking, and a power whose only combat lines are proc riders (no direct hit of its own) isn't treated as something you aimed and cast.

How often a proc actually fires isn't a flat percentage. Each proc piece carries its own PPM (Procs Per Minute) rating, built into the enhancement itself and mined from the game's own data, and the game works out a proc's chance to fire from that rating together with the power it is slotted into. The practical consequence is the part worth remembering: where you slot a proc changes how often it fires in play, so the same piece is worth more in one power than in another.

This entry deliberately stops there. The exact formula the game uses to turn a PPM rating into a per-use chance is not part of any data this tool holds, and a worked example built on a guess would be worse than no example - a precise, sourced treatment is queued for a later pass.

Source: this tool's own proc detection (the exact log-line shape a proc writes) and the PPM ratings mined from the game's own enhancement database.

5. Rarity tiers

Every enhancement set in the game (as opposed to a plain single-stat SO or generic IO) carries a rarity tier describing how uncommon it is to obtain - not a price. This tool's own catalog, mined straight from the game's data, knows 227 sets in total; 225 of them carry a tier: Uncommon (61 sets), Rare (83), Very Rare (10), PvP (9, arena-only), Archetype and Superior Archetype (26 each, locked to one specific archetype), and Winter Pack Series / Superior Winter Pack Series (5 each, from a past seasonal event). There is no "Common" tier in the game's own data at all. The remaining two sets - Cupid's Crush and Overwhelming Force - carry no rarity value in the game's own data at all; this tool doesn't guess one for them, and neither should you.

When advice mentions rarity, it's a shopping-source hint - "a Rare drop, may take some hunting" versus "an Uncommon, easier to find" - never a cost figure. Homecoming's player market moves on its own, and this tool has no price data, so it never states one.

Source: this tool's own set catalog and its tier counts, mined from the game's raw data dump.

6. Accolades

An accolade is a small passive bonus you unlock permanently by completing a specific set of badges (in-game achievements). Once earned, its bonus - extra Max Hit Points, extra Max Endurance, and so on - simply always applies. No slot, no power pick, nothing to activate.

Earning more than one accolade stacks their bonuses, and they stack as a percentage of your base stat - not compounding on top of each other:

This is also why advice about accolades always speaks in percentages, never a flat HP or Endurance number: your base Hit Points and base Endurance depend on your archetype (a Tanker's base is nothing like a Blaster's), and that per-archetype base isn't data this tool has - so it can tell you "+20% Max HP combined," never "+204 HP."

Verified in-game, and cross-checked against these four accolades' effect values in this tool's accolade data - all four match exactly.

7. "N of M sessions"

This tool scores your build against every session in your log that carries enough evidence to judge from - M is that total count. When advice cites something as showing up in "N of M sessions," it means the underlying issue - a damage type that hit you hard, a power's accuracy running low, endurance running dry - actually appeared in N of those sessions separately, not just once.

Why it matters: a pattern that shows up in most of your sessions is a real, recurring weak spot; the same finding in just one of five sessions might be a single bad night, not a build problem. It also directly affects how advice is ranked - how often something recurs is multiplied by how severe it was where it showed up - so a smaller issue that happens in every session can outrank a bigger one-time spike.

Source: this tool's own finding ledger, where each finding's weight is how often it recurred (the sessions it showed up in, out of the sessions with enough evidence to judge) multiplied by how severe it was.

8. Ticks

A tick is one individual application of an over-time effect. A damage-over-time power lands once - one hit roll, one connection - and then its effect re-applies itself on a fixed schedule for the next few seconds. Every one of those re-applications writes its own line in the combat log ("…for 7.08 points of Lethal damage over time"), and each such line is a tick. Heals over time work the same way.

Everywhere in this tool, ticks count in full toward total damage but never toward landed uses or per-hit averages - otherwise a power that ticks eleven times per cast would look like it "hit" eleven times, and a clean single-hit attack would look feeble beside it. See "Landed uses" below for the counting rule.

9. "Landed uses"

This is how the advice engine counts "how many times you actually used a power" for its damage math - specifically, how many separate times it connected with a direct hit, not how many lines it produced in the combat log.

That distinction matters because a single cast can print several log lines that all belong to the same use: an AoE hitting three enemies at once is one landed use, not three; a damage-over-time power ticking for several seconds afterward is still one landed use, not one per tick. Counting log lines instead would make a slow single-target attack look weaker than a wide AoE purely because the AoE prints more lines for the same one cast.

Source: this tool's own damage statistics, which count a landed use as one distinct instant carrying a direct (non-damage-over-time) hit - phrased this way deliberately, so an AoE's multi-target hit is never overcounted.

10. Enhancement Diversification

Slotting more of the same thing into one power stops paying after a point. The game keeps the first chunk of your enhancement in full, then hands back steadily less, and past the last threshold it keeps only 15% of everything you add. Six damage pieces in one attack do not give you six pieces' worth of damage.

The thresholds depend on what you are enhancing:

• Damage, accuracy, recharge, endurance, healing and every mez: everything up to 70% counts in full, then 90% of the next 20 points, 70% of the next 10, and 15% of anything past 100%.
• Defense, resistance, range and to-hit: the same pattern but it turns much earlier - full value to 40%, then 90% of the next 10, 70% of the next 10, 15% past 60%.

Source: measured against the game's own Detailed Info panel. One power's panel pins all four bands at once, because its four enhanced aspects sit at different points on the curve.

A fan-made tool. Not affiliated with NCSOFT or the Homecoming team. City of Heroes and related marks belong to their owners.