Converting monsters from Tales From The Infinite Staircase

[Cleon]

There shouldn't be a Will save to avoid the effect entirely since the rat has to make an attack first. At least that's the normal way these things work, though I'm sure there's precedent both ways. Are you worried it's too deadly otherwise?

It's not so much deadliness as that (a) "Will & Fort saves" is how a target resists phantasmal killer in 3E and (b) if it uses just one save we have to decide whether its Fort (since it's described as a "poison") or Will (since it's a "phantasmal"). If we have both we don't need to decide!

There are some spells that have an attack roll and two saves (like poison with its primary and secondary Fort saves vs. poison).

The AD&D version of the spell uses an "attack roll then save to disbelieve" mechanic, but it can make repeated attack rolls until it hits or the duration runs out. That's sort-of like your "hit then save" proposal.

 

[freyar]

Oh, ok. Attack roll, then Will, then Fort. Cha-based saves, I guess. And of course the rat can attack multiple times!

So we need to decide on Cha. Given the hp, the save DC shouldn't be too hard. I'd say Cha 13 or maybe 15. By the way, we need another odd ability score. How about swapping Str to 3?

 

[Cleon]

Oh, ok. Attack roll, then Will, then Fort. Cha-based saves, I guess. And of course the rat can attack multiple times!

Agreed!

So are we keeping the illusion (phantasm) descriptor then?

So we need to decide on Cha. Given the hp, the save DC shouldn't be too hard. I'd say Cha 13 or maybe 15. By the way, we need another odd ability score. How about swapping Str to 3?

Contrariwise, I feel the DC ought to be reasonably high otherwise there'll be little chance of it working. A phantasmal killer spell has a minimum DC of 16 (4th level spell so 14+ primary stat).

That suggests the Charisma ought to be 14+.

 

[freyar]

Illusion (phantasm) is a school (subschool), not a descriptor. Can Su abilities have that?

I'm ok with Cha 15. But these are going to be really low CR to have such a nasty effect. I mean, even 3d6 has a decent chance of killing a character at the likely CR. I'd like it to have a fairly low chance of succeeding (much like the cockatrice's petrification).

 

[Cleon]

Illusion (phantasm) is a school (subschool), not a descriptor. Can Su abilities have that?

It can have it if we want it to have it!

I'm ok with Cha 15. But these are going to be really low CR to have such a nasty effect. I mean, even 3d6 has a decent chance of killing a character at the likely CR. I'd like it to have a fairly low chance of succeeding (much like the cockatrice's petrification).

Well the original scenario is for 4th to 6th level characters, so ideally we want something that's a moderate threat to a single character of that level. (The way the adventure was set up it was one PC vs. one Nightmare Rat, and it didn't matter much if the Rat killed them since it was "only a dream").

So, assuming it's the lowest level (4th), the adventurer is likely to have enough hit points to survive the damage (even a wizard with an average Con score has 10 hit points and a 50-50 chance). Their good save is probably about +5 or +6 (base of +4 for levels, with at least a few extra points from abilities or resistance items) but their bad save might only be +1.

If we use plain HD + Charisma for the Rat's nightmare DC and assume it has Cha 14-15 then the nightmare bite will have DC 12.

What's the weakest opponent the Rat is likely to face?

I'm thinking Rogue, since they have poor Will and Fort save and mediocre hit points.

Let's see, I'll assume a 4th level Rogue with saves of Will +2 and Fort +2 and 14 hit points.

If this rogue gets bitten there's a 55% chance they'll save completely, a 24.75% (0.45*0.55) chance they'll fail the first save and take 3d6 damage and a 20.25% (0.45*0.45) chance they'll fail both saves.

In the latter case they die. In the 3d6 damage case they'll drop to the Dying condition if the damage roll is 14+ (enough to put their initial 14 hit points into the negatives, allowing for the 1 point of damage the bite itself does). The chance of that happening is 35 in 216, or about 16.2%. Multiply that by the 24.75% odds of them failing the first save but not the second and they've got an approximately 4% chance of being knocked into "Dying" by the first bite. (0.162*0.2475)

So, if we add the odds of "Dead" (20.25%) and "Dying" (4%) together, the weakest likely opponent has around a 1 in 4 chance (24.25%) of being killed or mortally wounded out by the first bite that hits.

Contrariwise, a strong 4th level opponent will have 30+ hit points so the damage doesn't pose an immediate threat, meaning they only go down if they fail both saves. Such a foe's saves are likely both good. Let's say +6, for a 75% chance of success. That works out to a 6.25% chance they'll fall to the first bite and an 18.75% they'd take the additional venom damage. On average it'd take roughly a dozen bite attacks to kill them from "single save failure" poison hits - 11 hits with its bite attack at 18.75% chance. With that many hits there's a 49% chance they'd roll a double save failure and get the "dies instantly" result.

More importantly, it's highly unlikely the Nightmare Rat would survive long enough in melee combat to get eleven hits in. It'd be lucky to hit twice before its opponent bashes through its 8 hit points.

Also, remember they don't have any Reach so most opponents will get an opportunity attack in unless the Rat surprises them.

Are those the kinds of odds you're after? I'd prefer something a little nastier. Maybe give it a +2 racial bonus or Ability Focus (phantasmal killer poison)?

Then again, I'd probably be using my Cleon Special Homebrew if I ever wanted to run a Nightmare Rat, so the issue is a bit academic.

 

[freyar]

Let's say it's a phantasm, rather than illusion (phantasm), just to make it less spell-like.

My feeling is that it might be better to boost the HD to 4 or 5. That gets another +2 on the DC and gives it a little more staying power. How about that?

Also, let's drop the "poison" from the phantasmal killer name, since it's basically the spell in an Su wrapper.

 

[Cleon]

Let's say it's a phantasm, rather than illusion (phantasm), just to make it less spell-like.

If forced to cut out one of the terms, I'd go for plain Illusion.

I don't feel "phantasm" is any less spell-like than "illusion" under the rules. They're both spell categories under the rules, just one's a school and the other a subschool. Besides, phantasms are a sub-category of illusion and the rules don't consider the possibility you can have one without the other. It's not life the Fear descriptor, where you can have a fear-creating spell that isn't mind-affecting or an illusion.

My feeling is that it might be better to boost the HD to 4 or 5. That gets another +2 on the DC and gives it a little more staying power. How about that?

I'm against adding a bunch of Hit Dice to a creature that only has one HD in its original version. I'd rather allow for the possibility of 4-5 HD while keeping the base HD at one by giving the Nightmare Rat a wide Advancement range.

So, do you prefer the current DC 12? It sounds like you fancy making the Rat rather low CR, in which case we'd want the save DCs to be relatively modest.

Also, let's drop the "poison" from the phantasmal killer name, since it's basically the spell in an Su wrapper.

We've already removed the "poison" from the name:

Phantasmal Killer (Su): Any creature bitten by a nightmare rat immediately sees an image of an incredibly fearsome beast. The victim must make a DC X Will save. If they fail, they take 3d6 damage and must succeed at a DC X Fortitude save or die of fear. This vision can never be reflected on the nightmare rat, but it acts otherwise like a phantasmal killer spell. This is a mind-affecting fear [illusion (phantasm)?] effect.

We just haven't updated the Working Draft yet.

 

[freyar]

Conversely, since all phantasms are illusions, you don't need to say something's an illusion once you specify it's a phantasm. I don't really mind much, but I would just like to change up the wording, so it's not so spell-like. Just make the last sentence "This phantasm is a mind-affecting fear effect." Or even "This phantasm illusion..."

If we're sticking to 1 HD, I'd definitely rather keep the DC and CR low, or else it will be a glass cannon.

 

[Cleon]

Conversely, since all phantasms are illusions, you don't need to say something's an illusion once you specify it's a phantasm. I don't really mind much, but I would just like to change up the wording, so it's not so spell-like. Just make the last sentence "This phantasm is a mind-affecting fear effect." Or even "This phantasm illusion..."

OK, let's use the "This phantasm is" and DC 12 approach and move on. I've always got my Homebrew for a nastier version.

Updating Nightmare Rat Working Draft.

If we're sticking to 1 HD, I'd definitely rather keep the DC and CR low, or else it will be a glass cannon.

Well it pretty much is a glass cannon, but I have no objection to aiming for a lighter version. It helps distinguish it more from my Cleon Special™.

 

[Cleon]

By the way, we need another odd ability score. How about swapping Str to 3?

So what are we doing about the odd ability score?

I'm leaning towards Int 3 rather than Str 3.

There's no mention of them being particularly large or strong, and the original is "semi-intelligent", which in AD&D has a range of 2-4. Admittedly the original's "Int: Semi (2)" puts its Intelligence at the bottom of that range at Int 2, but matching AD&D to 3E intelligence ranks is an inexact science.