Visions of Aestia

A few years ago, there were quite a few people with established 2E campaigns migrating to the slick new d20 mechanics. Many smaller RPGs went through a similar conversion with varying degrees of success.

If you’re running (or designing) a d20 campaign, it might be worth your time looking at Green Ronin’s new True20 system. Steve Kenson et al have made many small, incremental improvements that, taken together, produce a much slicker package than the standard d20 system. In my experience, it’s easier to play and easier to run.

While the True20 system includes a conversion index, it’s pretty superficial - enough for you to convert existing stat blocks, but not much more. So here’s a guide to the rest based on my experience.

There are four major subsystems that need to be converted. You can do them one at a time, and you don’t have to change all four of them - if you prefer the d20 version of one, keep it. I’ve chosen to convert all of them, though I’ve had to make some adjustments to keep my players happy.

The first system to look at is the magic system. The system is a modification of rules originally presented in the Psychic’s Handbook and reprinted in the Advanced Player’s Handbook.

Rather than rationing spells by level and casts per day, spell use is constrained by a fatigue mechanic. Essentially, spells are a special type of skill (with the versatility that implies), with the effects dependent on a skill roll versus a difficulty set by the desired effect. In some cases, the effect depends entirely on the value of the check result.

Will you players be happy with the new system? You will be as a GM or designer, because there is inherently a much smaller number of spells to learn and adjucate, and statting out high-level spellcasters will be a much, much more pleasant experience. For most players, I’ve found that the smaller number of spells is offset by the greater versatility of each spell. Getting rid of the hard limit on number of spells cast is also quite liberating.

The truth of the matter is that most players stick to a reasonably small number of spells for their casters anyway. The practical effect of the new system is to eliminate some restrictions and reduce the amount of rule lookup at the table. Always a good thing.

However, the knock-on effect on an ongoing campaign is something to consider. You’ll need to restructure five things - spellcaster classes, metamagic feats, spell restrictions, spells themselves, and spell-like abilities.

The primary issue with spellcaster classes is the “spells per level” and “spells per day” tables. It’s easy enough to just throw out the spells per day table - restrictions there are no longer needed. Spells per level is harder.

The True20 philosophy is that spell access is mediated through feats - you take a feat to learn a spell (possibly two spells if you follow the Blue Rose model). Since we haven’t yet redesigned that part of our campaign world, we’ll settle on a different model.

Each spellcasting class starts with 2,3, or 4 spells; use the existing per-level charts to decide which. I use half the total number of starting spells. According to the charts, a sorceror starts with 8 spells (5 cantrips and 3 1st level) and a wizard with 4 (3 cantrips and 1 1st level). I’d therefore start them out with 4 and 2 spells, respectively.

They then gain an additional spell every time their per-level chart adds another spell level. For example, a wizard traditionally gains 2nd level spells when he reaches level 3, and gains 3rd level spells when he reaches level 5. Under our new design, he would gain a single new spell at level 3, and not learn any new spells until level 5.

If you follow this guide you’ll eventually make other changes that will obsolete this decision; but if you stop here or decide not to make those other changes, you’ll at least have a somewhat reasonable basis for futher work. You can always tune these numbers up to match your own campaign world more closely.

Metamagic feats are next on the agenda. Usually, they force you to use a higher-level slot to cast a given spell. Since we don’t have spell slots, we need to increase something else. Looking at the feats already converted, it’s easy to see that increasing the fatigue difficulty has the desired effect. In most cases, using the feat on a non-fatiguing spell should also make the spell fatiguing at the new difficulty level. Speaking simply, we’re saying that using metamagic is more tiring. Same effect, different mechanic.

Restrictions by school or descriptor can be a little trickier, because the smaller number of spells means you’re giving up more. Usually the easiest thing is to just get rid of the restrictions altogether. The next easiest is to assign some descriptors and make the restrictions penalties to fatigue/skill checks instead of outright bans.

When converting spells, you need to decide on difficulties and whether spell scales. Spell chains make your life easier. For example, the “Summon Monster” series is a chain of 9 spells. Here you’d want to make a higher check result produce a tougher monster. Alternatively, you could have a fixed difficulty and base the toughness on the spellcaster level (in this case, failing would mean nothing was summoned). I’d suggest making a spell fatiguing by default.

I don’t have any words of wisdom with regards to spell-like abilities. If they’re equivalent to an existing spell (or one you’ve converted), probably the only change worth making is work out the number of ranks used to cast it. Most of the time they say something like “as a 7th level sorceror” so just add three to that level and you have the number of ranks to use. A useful thing for the GM would be to work out the results of taking 10 when writing up stat blocks.