More necromancers

So a while ago I imagined a Necromancers game and proposed a broad skills-based system. Dan disagreed and has put forward a class-based game with specific abilities. After much distraction doing other stuff, I have an initial idea for this that I’m going to play around with.

Although I originally mentioned a BRP-like system, and I still think that would work, I've been playing around with ideas for theme-based organic magic recently. Which is to say, ways of combining small numbers of generic keywords to create a variety of interesting effects. I feel like this could avoid the need for massive lists of specific spells, and allow player creativity,

Spellcasting

The basic idea is that magic – which should be the majority of the cool stuff going on – will be modelled as a combination system. There are Talents (what you do) and Spheres (what it relates to) which can be combined to model a wide range of necromantic magic, without creating specific spells. The Talents are Commune, Evoke, Manipulate and Assume. The Spheres are Darkness, Essence, Bone and Beast.

Spells are cast by rolling up to 5 d6s, at the caster’s choice. Each roll of 4+ is a success. On a double, the spell misfires in some way – low numbers will tend to sputter out or go awry so they have little effect, while high numbers go out of control, possibly doing what you intended but also wreaking havoc. As a result, rolling more dice will produce a more powerful spell, but will also increase the risk.

By itself, the misfire rule would be annoying. However, the caster’s aptitude makes a great difference. This allows you to ignore doubles, based on your Mastery, making it advisable to stick to your favoured spells.

Ignore numbers

You rank the Talents and Spheres from 0-3, and when casting a spell, add these numbers together to find your, um... Mastery? Sure, why not. You can ignore any doubles less than or equal to your Mastery. This means that your best combination can always be safely cast (3+3=6), your worst combination will be pretty risky except at low power, and most spells can be cast with 2-3 dice for only moderate risk.

Of course, this means there’s always a risk for anything but your very best combination. Or do I want to have improved skill cancel out specific numbers of doubles, making casting below your skill level always completely safe? Let’s look at some numbers.

For 2d6, the probability of a double is 1/6

For 3d6, the probability is... ouch. Okay, I can’t actually find any guidance on this question from people who are willing to talk the right level of maths. Which is to say: I can find people who answer specific questions about this with specific numbers, and I can find people who refer obliquely to complicated maths, but not anyone who will lay out clearly how I would calculate this stuff for myself. I’m pretty sure it’s a factorials thing, but I’m happier with my ability to tediously lay out charts in Excel than with my ability to guess at statistics. And doing factorials with fractions is a nightmare.

So it looks like probabilities go something like: 0.1666..., 0.444..., 0.722... and I can’t be bothered with the ghastly cut-and-pasting required to do 5 dice, but it should be around the 0.9 mark. Assuming I didn’t mess up. The figures match the specific figures I got elsewhere, so great.

This means that if you’re casting a four-dice spell, you have a 72% chance of something going wrong. Unless you’re casting your very best spell, there’s at least a 12% chance of a miscast, and this will generally be more like 36% as the average spell rating will be 3. Okay, you’re not likely to cast your rubbish spells that often, but basically you have a substantial chance of problems on any but your most favoured spells, although in many cases this will be a case of overpowering them rather than wasting your action, because low doubles get lost first.

Dice-negating

What about cancelling dice instead? That is, on favoured spells you can ignore specific dice for the purposes of doubles, rather than doubles with certain numbers? So if you rolled 4, 4, 4, 5, 6 you’d be able to ignore the triple if you had two Mastery. I’d need to adjust the ranks, probably using 0012 rather than 0123.

That’s... at least equally difficult to calculate, if not more so, because I have to care about number of pairs rather than their existence. Thankfully, someone has done it because Yahtzee exists, although again they only vaguely mutter about binomial expansion without explaining it.

With only 3 dice, the most likely common minimum (rolling 2 dice for 4+ doesn’t seem like a gamble many people will take often), there’s a 3% chance of needing 2 mastery and a 42% chance of needing 1.

For four dice (I did this one first, which is why it’s longer): Four identical = 6/1296, Three identical = 120/1296, Two pairs = 90/1296, One pair = 720/1296

So there’s a 6/1296 chance (0.00463) of needing 3 Mastery, a 16% chance of needing 2 Mastery (a triple or two pairs can both be cancelled by negating two dice), and a 55% chance of needing one Mastery.

With 5 dice, there’s a vanishingly small chance of needing 4 Mastery, so small that I don’t think it’s worth worrying about ever. There’s a 5% chance of needing 3, a 38% chance of needing 2, and a 46% chance of needing 1.

On the whole, then 2 Mastery will be enough the overwhelming majority of the time. I suppose I could introduce a rule that when cancelling pairs, you have to cancel both dice of the first pair before you can cancel the second pair, but that seems a bit clunky.

Highs and Lows

A simpler alternative would be the ever-popular 1s rule. Rolling a 1 would make the spell fizzle, but Mastery allows you to ignore 1s. Similarly, 6s might make the spell a bit more powerful than you intended, but Mastery absorbs that (whether you want it or not) although they still count as a success. If you roll a 1 and a 6, you could decide which to cancel first. You’d of course get more 1s and 6s with more dice, but with Mastery you can ignore many of them. This is probably a lot simpler, I wish I’d thought of it before. But I probably want to use d10s rather than d6s here, and go for a 5+ success.

Spells

Here's a table of the Spheres and Talents, with some example spells that might be possible.

	Darkness	Essence	Bone	Beast
Commune	See in darkness Detect shadow beings	Detect souls See ghosts Speak with dead	Find bodies Sense skeletons Forensic necromancy	Sense sinister animals Speak with beasts
Evoke	Conjure darkness Cause blindness Cause fear	Animate dead Death bolt	Conjure skeletons or skeletal constructions	Summon bats, wolves, rats, cats
Manipulate	Alter shadows Create shadow servant	Influence creature Compel Ghost	Warp enemy Shatter bones	Turn into cloud of bats
Assume	Travel through shadows Shadow aura	Heal pain or cuts Drain life Ghostly “rider” aids you	Grow skeletal claws or wings Mend bones	Take on bestial traits

Draft system

So, under this draft I'm using the high-and-low system.

During character generation, you assign numbers 0,0,1,2 to each of the Spheres and again to each of the Talents. When casting a spell, you determine which Sphere and Talent combination it falls under and add these scores to find your Mastery.

To cast a spell, you roll between 0 and 5 d10s. A score of 5+ grants you one success, making the spell more effective. To achieve significant effects, you need larger pools. The choice of how many dice to roll is entirely up to you; you decide how much power you want to try and draw on.

Rolling extra dice is risky because you're more likely to lose control of the spell. Any roll of a 1 is a Fizzle, as the spell dissipates prematurely or goes awry in some mundane fashion; there may be minor effects from the magic, but effectively it's a dud. Any roll of 10 is a Miscast, as the spell's energies overwhelm you and you lose control; the spell goes off and will typically achieve more or less what you wanted (10 is still a success, after all), but it's also going to have unexpected consequences.

Mastery helps you to control your spells without untoward happenings. You can ignore a number of Fizzles and Miscasts equal to your Mastery - this doesn't affect the number of successes you get (the dice aren't discarded), so rolling 10,10,10,2,4 with Mastery 3 is still a successful cast.

Additional successes don't have to change the result of the spell. If you only want to achieve a minor result, and roll four successes, it doesn't force you expand the spell's effect - it's not much of a success otherwise.