Some NPC abilities allow the target to make a resistance check, and the notation on some of them is mysterious to me. As an example, the Manifest Earth Kami's Eruption ability allows a "TN 4 Fitness check (Air 2, Water 5)". Does this mean the TN is different depending on the Ring you use? In this example, that would mean the TN would be 4 if using the Earth, Fire or Void rings, but TN 2 for the Air ring and TN 5 for the Water ring.

And if this is the case, how is this determined? Is it based on the NPC's Demeanor, or just by common sense? I'm trying to convert some creatures from 4th edition and this has been gumming me up. It seems to only affect Adversary class NPCs, and only for especially formidable abilities, but I'm sending people into the Shadowlands, so...

13 hours ago, zamarren said:

Some NPC abilities allow the target to make a resistance check, and the notation on some of them is mysterious to me. As an example, the Manifest Earth Kami's Eruption ability allows a "TN 4 Fitness check (Air 2, Water 5)". Does this mean the TN is different depending on the Ring you use? In this example, that would mean the TN would be 4 if using the Earth, Fire or Void rings, but TN 2 for the Air ring and TN 5 for the Water ring.

Correct. Core Rulebook, p.296.

13 hours ago, zamarren said:

And if this is the case, how is this determined? Is it based on the NPC's Demeanor, or just by common sense? I'm trying to convert some creatures from 4th edition and this has been gumming me up. It seems to only affect Adversary class NPCs, and only for especially formidable abilities, but I'm sending people into the Shadowlands, so...

I think mainly it goes to the 'common' sense (air quotes because sometimes it requires extra puzzling out). Air, staying mobile and evasive, makes good sense for an easier "missed me" TN.

Water, whose approach for Fitness includes "moving around obstacles" and "rolling with the punches" seems like it could also be a good choice to get around the Earth exploding underneath you. Not to mention, being in Water stance gives you a bonus action (albeit unrolled) during your turn.

Meanwhile Earth approach includes "hiding by s tanding still, taking a hit ." (emphasis added). Void has "taking hits directly." So why are they better than Water?

Well, the Manifest Earth Kami's demeanor is "Obstinate" which is a +2 Water TN and -2 Air TN. So Air good, Water bad.

Though as you point out, the TN for that ability only goes up by 1 for the Water Stance folks.

On 2/8/2019 at 4:30 AM, zamarren said:

Some NPC abilities allow the target to make a resistance check, and the notation on some of them is mysterious to me. As an example, the Manifest Earth Kami's Eruption ability allows a "TN 4 Fitness check (Air 2, Water 5)". Does this mean the TN is different depending on the Ring you use? In this example, that would mean the TN would be 4 if using the Earth, Fire or Void rings, but TN 2 for the Air ring and TN 5 for the Water ring.

And if this is the case, how is this determined? Is it based on the NPC's Demeanor, or just by common sense? I'm trying to convert some creatures from 4th edition and this has been gumming me up. It seems to only affect Adversary class NPCs, and only for especially formidable abilities, but I'm sending people into the Shadowlands, so...

Yes, as stated previously the stance determines the approach taken to resist effects, but the opponents demeanor doesn't usually have anything to do with the TN to resist their abilities.

I tend to think of resisting with air as using precision/guile, earth as using mental and physical strength or stamina, fire as dexterity /creativity, water as constant fluid motion and adaptation, and void as suffering. When creating new effects or converting abilities think of the best and worst ways to resist it (mentally and physically), everything else falls in the middle for the TN.

When it comes to resisting, remember PCs and NPCs can only change stance on their turn, so the option to use a more favorable stance (lower TN) to resist is not always an option.

It might be a good idea to either give high vigilance PCs the opportunity to assess the challenge before choosing their stance (initiative phase), or ask for default stances (like marching order/formation), otherwise they default to Void. For NPCs, as you suggested, demeanor might be a good way of assigning a default stance, or assume their stance defaults to whatever is their highest ring.

The variable resistance TNs are actually based on a rock-paper-scissors mechanic. So if you have a Fire-based attack, the resistances would be harder for Air and easier for Water, for instance. It's reversed for Earth. Void doesn't participate (its effects don't have variable TNs, and Void always resists with the base TN). Oddly, this rock-paper-scissors mechanic also applies to shuji (the few that have resistance rolls), not just overtly elemental things like invocations.

Note that some effects which aren't tied to a ring do have variable resistance TNs, though - a lot of NPC abilities (like the Oni's Dread Bellow) are available 'on demand' from any stance, but still have fixed 'better' and 'worse' rings to resist it with.

It's also worth reminding that wound penalties are ring-limited... and being wounded in your primary ring can make the alternate rings more useful. Remember, a +1 TN is about equal to -2 dice (really, about 1.9 ... a +3 TN is almost nullifying the ring..)