Sorcery, Building Powers, and Rolls

[philosophyguy]

I just purchased Thaumatology: Sorcery and am loving the work that was done in this volume.

I've always struggled with building powers and I'm confused how some of the powers were built in this book.

1. When does a roll lower the cost of a power? On page 12, the book states that most spells don't require a casting roll. Some spells may require a skill to use the spell, like Innate Attack for an offensive power.

But, of the spells that require a casting roll, only Haircut includes a negative modifier (Requires DX vs. HT roll, -10%). Every other spell that requires a casting roll does not include a Requires Attribute Roll modifier. It's not a matter of whether the spell is resisted; both Haircut and e.g. Animal Control are resistable but only Haircut includes the modifier.

2. What requires an Innate Attack roll? No Smell and Flesh to Stone are both afflictions. No Smell requires an Innate Attack roll but no casting roll. Flesh to Stone requires a Will casting roll but no Innate Attack roll. I can't find a pattern among the affliction-based spells for why they should be one instead of the other.

Any help on understanding how these powers were built so I can be better at creating powers in my own games would be much appreciated.

[weby]

Originally Posted by philosophyguy

I just purchased Thaumatology: Sorcery and am loving the work that was done in this volume.

I've always struggled with building powers and I'm confused how some of the powers were built in this book.

1. When does a roll lower the cost of a power? On page 12, the book states that most spells don't require a casting roll. Some spells may require a skill to use the spell, like Innate Attack for an offensive power.

But, of the spells that require a casting roll, only Haircut includes a negative modifier (Requires DX vs. HT roll, -10%). Every other spell that requires a casting roll does not include a Requires Attribute Roll modifier. It's not a matter of whether the spell is resisted; both Haircut and e.g. Animal Control are resistable but only Haircut includes the modifier.

The basic idea is that if there is no roll required as base then you get a reduction in cost to include such.

If you look at he animal control you see that it includes malediction and if you read the malediction enchantment in characters 106 you can see that it includes the text "To determine if the attack succeeds, roll against your Will.." and thus the malediction cannot get a discount for something already included.

The same goes for some advantages like warp or healing that have already a built in required roll.

If you look at the haircut description you can see that it uses telekinesis and as telekinesis does not include any such required roll to use nor do any of the modifiers used, you get a reduction to cost for requiring a roll.

2. What requires an Innate Attack roll? No Smell and Flesh to Stone are both afflictions. No Smell requires an Innate Attack roll but no casting roll. Flesh to Stone requires a Will casting roll but no Innate Attack roll. I can't find a pattern among the affliction-based spells for why they should be one instead of the other.

Any help on understanding how these powers were built so I can be better at creating powers in my own games would be much appreciated.

A base affliction requires an innate attack roll unless modified by malediction(or a few other effects like emanation). See characters 35. "By default, Affliction is a ranged attack with... .. although you can apply modifiers to change these statistics" so it requires an innate attack roll to hit.

Flesh to Stone includes malediction (characters page 106) that starts "Your attack is not a conventional ranged attack; it works more like a
Regular spell.. " and later has the will roll part I quoted above.


Edit: So simplified: Malediction changes a lot of things if included. Without it innate attacks and afflictions require to hit rolls, with it will rolls. Also without it there is no activation roll as default, with it there is.

[Kromm]

Originally Posted by philosophyguy

1. When does a roll lower the cost of a power?

When neither the underlying advantage nor modifiers other than Active Defense, Requires (Attribute) Roll, Requires (Skill) Roll, or Unreliable require such a roll. Many advantages require a roll; Mind Control is one example (a Quick Contest of IQ vs. Will is built in), and Healing and Warp are two others (IQ rolls are built in). Some modifiers other than those named above require rolls, too; notably, anything with Malediction picks up a Quick Contest of Will vs. either Will or HT, depending on the underlying advantage. The limitations Active Defense, Requires (Attribute) Roll, Requires (Skill) Roll, and Unreliable exist mainly for the purpose of adding rolls to abilities that don't require them for one of those other reasons.

Originally Posted by philosophyguy

2. What requires an Innate Attack roll?

Any offensive ability that doesn't require a resistance roll and isn't an Aura, Emanation, or other essentially passive effect. Notably, any Affliction, Binding, or Innate Attack not modified with Malediction, and any advantage modified with Ranged or Weaponized. Maledictions and anything that works like them (Mind Control, Neutralize, Possession, etc.) use resistance rolls, not Innate Attack rolls.

All of this is explained in detail in GURPS Powers. Sorcery hides that behind the curtain and directs the reader interested in creating new spells to that work.