Off the Path: HERO Power Construction

A brief diversion on the Words of Power exploration, I thought it worth providing a bit of an overview of how powers are constructed in HERO System. This looks like it will become important soon.


Powers in HERO are based on effect, with descriptors added to give flavor and something to hook abilities on. At its root, a fireball and a lightning bolt are very similar: they do damage at range. In HERO 6e terms, and for the sake of argument, they both use the Blast power (previous editions it was ‘Energy Blast’, but the same power was used for energy and physical blasts. Blast costs 5 points per 1d6 damage, and has a range directly proportional to points. The descriptors provide narrative and descriptive elements that can be applied, and can influence how these interact with other powers. For instance, a staff that augments fire powers can make the fireball more powerful, but do nothing for the lightning bolt. For this example, we’ll work with an 8d6 blast in both cases (worth 40 points, the Base Cost).

That is at the base… but powers are not just the base effect. In this case ‘fireball’ implies that it fills a circular area, while a lightning bolt probably zaps anything between where the bolt started and where it ends. The fireball might be best defined as having a ‘radius area of effect’ that determines how much gets charred, and the lightning bolt could be defined as having a ‘line area of effect’. This sounds like it should make the spells better than without, providing an advantage. It would be reasonable to expect this to be more expensive… and it is.


The 40 point base cost is just where we start. Advantages are measured in units of “+¼” (and presented in simple form: the next step up from a +¼ advantage is a +½ advantage, not a +2/4 advantage). You  multiply the base cost by (1+sum of advantages) to get the Active Cost, the measure of how powerful the power is. A 4d6 Blast (20 Base Cost) with +1 of advantages would have an Active Cost of 40, same as the 8d6 Blast (and in principle is as powerful — it might do less base damage, but the advantages might make it better than the 8d6 Blast, such as if it were armor piercing and able to ignore some armor, or indirect and not needing line of effect to the target).

In the Pathfinder Roleplaying Game, fireball has a 20-foot radius. This doesn’t align exactly with HERO System (which uses metric on a hex grid, each hex being 2 metres across), but 20 feet is four squares, and if I equate that to four hexes that would be 8 metres. In reality this is a little more than 25 feet, but in game terms I’ll consider this a rounding error. A power in HERO with an 8-metre radius would have a “+¾” advantage. The fireball has an Active Cost of 40*(1+¾)= 70 points.

With the lightning bolt I’m going to do something different. In the Pathfinder Roleplaying Game this is a 120-foot line, but instead I’m going to make it indirect, a +½ advantage that means I don’t need line of effect to my target. Unlike the fireball I affect only a single target, but I all lightning from the sky to strike my enemies, and don’t need to be able to reach them directly. The indirect advantages increases my Active Cost to (40*(1+½)=) 60 points, but ‘calling lightning from the sky’ sounds like I need to be able to see the sky. That limits how I can use the spell, it’s not going to be much use underground.


Limitations serve two purposes in power construction. They lower the Real Cost of a power to make it affordable (in a Heroic-grade game a 60- or 70-point power would consume a very large fraction of a character’s build resources), they provide restrictions on the use of a power to make the powers more interesting to play, and they help make the powers more distinct.

As advantages, limitations are measured in units of ¼, but are marked as negative values as a reminder. Where the Base Cost is multiplied by (1+advantages) to get the Active Cost, the Active Cost is divided by (1+absolute value of limitations). That is, a 60 Active Cost power with -½ limitation would be worth 60/(1+½)= 40 character points.

In the Pathfinder Roleplaying Game, casting fireball has verbal, somatic, and material components. In HERO terms these would be Incantations (verbal utterance for the purpose of activating power and no other purpose, recognizable as unusual; preventing speech prevents the power from being used: -¼), Gestures (free and visible movement for the purpose of activating power and no other purpose, recognizable as unusual; preventing free movement prevents the power from being used, -¼), and a Focus (“Obvious Accessible Focus”: it’s clear that the bat guano and sulphur are used for unusual purpose, and thus ‘obvious’, they can be knocked out of hand (spoiling the spell) with a single action, and thus ‘accessible’, -1… foci are worth a lot in HERO). This is a total of -1½ limitation. This reduces the Real Cost to (70/(1+1½)=) 28 character points. Still awfully big for a heroic-grade HERO campaign, but you wouldn’t often see a starting PC with a 70 Active Point spell.

The lightning bolt, on the other hand, requires some more adjudication. There actually isn’t an inherent “must be able to see the sky” limitation, so the GM will need to determine a limitation value based on campaign expectation. If the campaign is largely set outdoors, this might be only a -¼ limitation: the sky is almost always available. If the campaign is in the Underdark and the sky is only rarely visible it might be -1½ (or even more! and this is probably a silly spell to pick). I’m going to guess here and say that the spell is usable roughly half the time, which is a -1 limitation (and I’ll be strict — if I made it a -½ limitation I’d likely still let it work in caves and rooms with windows, as long as the sky was reachable). I’m going to say that this spell has verbal and somatic components (-½ together), but that each casting consumes a wand made from the branch of a lightning-struck oak (OAF expendable, hard to get: -1¼). This gives a Real Cost of (60/(1+1.75)=) 21.8181… points — which in HERO rounds down to 21 points to 22 points.

Thanks to Chakat for the correction, I was misremembering a different example. Rounding in HERO is to the nearest integer, with half-points being rounded in the character’s favor. The only exception I can find is that the figured SPEED attribute always truncates — a character with Dex 18 would make DEX checks at 13- (i.e. 9+18/5 = 12.6, rounds up to 13) and have a base SPD of 2.8 (1 + DEX/10), which gets treated as SPD 2 for determining actions.

Closing Comments

This has been a brief explanation of power construction in HERO System. Even just as far as I’ve gone here, the flexibility inherent in the system should be evident… and I left out some of the funkier options, such as:

  • Naked advantages, advantages bought ‘as powers’ that can be applied to other powers. Buy an advantage as its own power, such as being able to Autofire ‘any weapon’ up to a certain Active Cost: take the Active cost of the biggest effect the Autofire can be used with, multiply by the Autofire advantage cost, and treat the result as the base cost of the ‘Autofire power’.
  • Partially-limited powers, where you can apply limitations to some but not all of a power. For instance, the 8d6 ‘fireball’ above has Gestures, Incantations, and OAF limitations. The spell could be written as being 6d6 with those limitations but having 4d6 more power available if other limitations (such as Extra Endurance, Extra Time and Concentration, say) are applied. You can cast a 6d6 fireball ‘normally’, or exert yourself (Extra Endurance, Extra Time, and Concentration) to cast a 10d6 fireball. The Active and Real costs of the two pieces would be calculated and added together to find the final values for the spell.
  • Power frameworks, where thematically related powers are grouped together to reduce their Real cost. This gives you more powers available at once, but there are restrictions on how you can use them. For instance, a ‘multipower laser rifle’ might have several ‘configurations’ that allow you to use Blast, Killing Attack, each with Autofire or Armor Piercing or Area of Effect… but only one configuration at a time. Lots of options, cheaper than getting six different items, but only one is usable at a time.

Hopefully this will help make my next Words of Power articles easier to understand. I’m pretty sure I can lean on this power construction mechanism to build and apply the Words of Power framework I’m devising.


  1. Chakat Firepaw

    A little correction:

    Rounding is done mostly normally to the nearest whole number, but with .5 rounding in the character’s favour rather than to the even number. So 21.82 rounds to 22, not 21.

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