Latest revision as of 13:14, 7 December 2017

Potency is a concept that is not, at its core, unique to Trinity, but this particular application of the concept is, so far as the d20 System as a whole is concerned. Ironically, this concept is heavily inspired by D&D 4th Edition.

Potency was born out of the desire to standardize the caller's eikons in order to reduce player workload in understanding how each summon worked. By invoking a common table of values, it was believed that we could reduce lookup times and make it easier for players to understand how the eikons compared to each other in terms of combat value. However, since that initial inception, it has been found that the potency concept is also incredibly helpful in encounter design and class balance.

Potency is currently a work-in-progress. Moving Trinity into a potency-based system is yet another departure from core d20, but one that will undoubtedly be significantly rewarding in terms of easing play and making class balance that much easier.

Overview

Level-based scalars in spell design in d20 was a solid concept, and allowed for casters to become more effective as they gained levels. While this paradigm works in a "linear warriors quadratic wizards" setup, with the introduction of maneuvers to Trinity and the massive class rebalancing (which is currently still in progress as of 15-10-21), level-based scalars are no longer sensible.

Of primary concern is the fact that level-based scalars introduce planned obsolescence into spell design: while magic missile retains some punch at higher levels, the fact is that it is simply an ineffective spell once characters enter high level play. Much of Trinity caster redesign has focused on reducing the total number of spell levels for the majority of casting classes. As such, allowing lower-tier spells to retain their power at higher levels is a solid way of allowing casters to function for extended periods of time, alleviating the "15 minute workday" problem.

Potency is the means by which this is accomplished. Rather than fixed damage codes for individual abilities, any ability that has a numerical value attached - primarily damage and healing, but not limited to these - instead has a potency, which is a damage code that scales with character level. A spell may say that it deals potency 4 fire damage; for a 1st-level character, that spell deals 1d2+9 damage, while for a 20th, it deals 2d8+55 damage. The relative effectiveness of the spell remains the same over the character's lifetime.

This also resolves issues of multi-classing at higher levels being ineffective. A potency 4 effect is always a potency 4 effect; if a 19th-level einhander decides to take a level of mage, the spells they can access will be just as effective as those of a character who has been a mage all their life. The distinction is that the 20th-level mage will be able to cast those spells effectively all day, while the 19th-level einhander/1st-level mage will have only a few MP, and must be significantly more sparing. Likewise, the mage will have access to effects that can hit multiple targets, have longer durations, or have higher potency.

Potency 12 is considered the damage cap: the overwhelming majority of abilities in this system do not allow you to make an ability's damage exceed potency 12. If an ability allows you to break the damage cap, and you go above potency 12, the result is equal to a potency 12 effect plus the amount listed in the "+1" category for each point of potency over 12, with the total rounded down. This addition is due to math: potency is linear, not multiplicative, across potency values, and each potency value scales linearly with level.

Example: Leon is a level 11 lancer, and he has an ability that allows him to break the damage cap with a specific maneuver. His total potency with that maneuver for an attack is 16, so his damage expression is 3d10+124, plus an additional (12.5 x 4 = 50), for a total of 3d10+174. The average damage output of this ability is 190. A theoretical class with a "d16 hit die" would have base 30 hit points, plus 15 per level past 1st; assuming a 10 Con and at level 11, such a creature would have 30 + 10 + (10 * 15) = 190 hit points, which demonstrates that this math checks out.

The table of potency codes is listed at the top of this page for ease of reference in play.

Potency and Size

Potency is modified to account for differences in size. This has two effects.

When a creature makes a targeted attack, the potency of that attack is reduced by 1 for each size category the target is larger than the attacker, or increased by 1 for each size category the target is smaller than the attacker. If the potency would be reduced to 0, it is instead reduced to half 1 potency; if it would be reduced below 0, the attack deals no damage. This effect does not allow you to break the damage cap.

When a creature makes an area attack, if any creature in the area has a space that is larger than the effect's radius, or half its length if a cone, reduces the potency damage it takes by 1 for each size category difference. If the potency would be reduced to 0, it is instead reduced to half 1 potency; if it would be reduced below 0, the attack deals no damage.

Half and Double

Some effects will call for half potency, while others will call for double potency.

In the event of a half descriptor, roll the indicated potency normally, then halve the result, rounding down. In general, higher-potency effects will not use half, but will instead simply use a smaller potency value.

In the event of a double descriptor, roll the indicated potency normally, then double the result. In general, lower-potency effects will not use double, but will instead simply use a larger potency value.

Design Notes

June 18, 2016: Complete revamp of potency calculations. Potencies have sensible average values, and the deviation from that average is roughly 10% for a given potency. Thus, any given potency roll should fall within 10% of its expected value; this feels like sufficient variation to not make things too predictable, while maintaining the utility of potency (which giant dice ranges fail to actually achieve).

Feb 6, 2017: Yet another revamp of potency calculations. This is due to my loss of the calculations when my laptop got smashed, so I had to redo them from the ground up. Earlier I had made note that some of the potency values seemed a bit off, and were ramping faster than expected; this has been resolved in the new values. Specifically, we now have true parity between potency values and hit point calculations (ie, a potency 6 attack against a character whose class gives them 6 healing surges as a base will always take them out around 50% of the time).

Note that every 2.5 points of Constitution you have above or below 10 will increase or decrease the potency required to one-shot you by 1 in that direction. So a character with a "d6 HD" class with a 12 Con effectively has a d7 HD (with a commensurate 50% chance to be one-shotted by a 7 potency attack), while a character with an 8 Con would effectively have a d5.

At even levels, due to potency only scaling at odds, your chances of surviving an equal-potency attack increase, usually significantly at lower levels and not significantly at higher levels. I may need to do some math on this, it's possible we may need to move to a "potency scales at every level" paradigm.

Dec 7, 2017: MATHS is a thing! Since the birth of this idea, I've struggled with "how do we handle static values," since something like fire resist 5 is simply more useful at some levels than others. However, in pondering on how to handle the armor problem today, it finally occurred to me - the solution has been staring me in the face this entire time. Potency values are derived from a static value that is then modified to give them a 10% spread around that value, and dice applied. Which means that if we use that static value for things, that gives us a solid baseline to work with - and results in still-sensible values!

For instance, let's say that you have fire resist (power 3), and you get hit by an effect that does potency 5 fire damage. Potency 5 is 1d4+10, so between 11 and 14. Your power 3 fire resist reduces that damage by 7, so now the possible range is 4 to 7. Potency 2 is 1d2+4, which has a range of 5 to 6. You just effectively turned a potency 5 effect into a potency 2, with just a little math.

This means we can have "static" values again, but they shift and change in response to levels, just like we wanted damage output to do.

I'm not sure about the name for name, but I like the kind of scheme going on with the names (potency and power, power and potency). Easily abbreviated, as well, to POT and POW.