Adjudicating Power for Noncombatant Monsters

[willpell]

It's relatively easy to figure out the power level of a monster when it comes to combat situations - compare its damage output to existing threats, its HP and AC and so forth - not effortless, but relatively straightforward given the volume of information that's available. What's harder is guessing whether a bonus is too generous when it comes to a monster whose purpose isn't as straightforward as "bash and get bashed until one side stops moving".

Case in point - I decided that in my game, I didn't like for my version of the Yuan-Ti to be able to shapeshift into snakes, so I dropped their Alternate Form ability in exchange for some skill bonuses. I'm portraying them as a race of secretive infiltrators and manipulators, sowing corruption in human society rather than openly fighting, and it bugged me how many skills they were missing. The skills I picked were Balance, Escape Artist, and Move Silently to represent the graceful, liquid movements of someone who's part snake, Bluff and Sense Motive for their ability to deceive people (both by directly lying to them and by figuring out what they want to hear so as to choose a "strategic truth" that will lead them into ruin), and Sleight of Hand for a little of both (it remains usable only while trained, they just get good at it really easily). But the question is, how much of a bonus is appropriate?

I'm giving them exactly what they want to be what their campaign role is intended to be, but I want to keep things more or less balanced with the race remaining playable. Alternate Form is a fairly strong ability to give up, but is it worth +2 each to those six skills on a race with 4d8 racial HD? What about +4 to the same skills? Weak, strong, absurd - I have no real way to guess. If I wanted to godmod them as a plot device it wouldn't matter, but I'm aiming for something a little more nuanced, so the question ultimately becomes how powerful Alternate Form is compared to boosting these skills.

[Urpriest]

For skills, I'd look at what the PCs can get at this level. Think about how often you want these guys to succeed on some task, then aim the bonus around there.

[willpell]

For skills, I'd look at what the PCs can get at this level. Think about how often you want these guys to succeed on some task, then aim the bonus around there.

I don't know how to adjudicate that; I know of no way that a PC can get bonuses to skills that can exceed max ranks, except for feats and races. And I have absolutely no clue how much Alternate Form into vipers is worth compared to any number of feats.

[Urpriest]

I don't know how to adjudicate that; I know of no way that a PC can get bonuses to skills that can exceed max ranks, except for feats and races. And I have absolutely no clue how much Alternate Form into vipers is worth compared to any number of feats.

By "the PCs" I meant your PCs.

For example, let's say that your PCs' highest sense motive is +17, and you want the Yuan-Ti to be able to lie to them roughly half the time. Then give them a sufficient racial bonus so that their total Bluff is around +17.

Yes, this doesn't tell you what Alternate Form is worth. But Alternate Form's worth is highly dependent on the scenario anyway. Alternate Form into a snake is almost certainly not contributing to these guys' CR, but neither would moderate skill bonuses. Don't think of it as a trade of features of equal value, but of a change to make the Yuan-ti more in line with the tactics you want them to use.

[willpell]

By "moderate" do you mean the +2 that most races give? I eyeballed it at +4 instead to make a more significant difference; this is closer to the benchmark for animals with a native ability to do something (sometimes they get +8 or more), since deception and manipulation are pretty much their entire shtick (they're not as murderous as standard Yuan-Ti, more like doppelgangers or succubi in terms of their MO, messing with stuff behind the scenes and having plots within plots and so forth). So +4 each to 6 different skills. Overkill?

[Urpriest]

By "moderate" do you mean the +2 that most races give? I eyeballed it at +4 instead to make a more significant difference; this is closer to the benchmark for animals with a native ability to do something (sometimes they get +8 or more), since deception and manipulation are pretty much their entire shtick (they're not as murderous as standard Yuan-Ti, more like doppelgangers or succubi in terms of their MO, messing with stuff behind the scenes and having plots within plots and so forth). So +4 each to 6 different skills. Overkill?

Think about it like this: a low-level invocation for a warlock is +6 to a bunch of skills. So +6 to a bunch of skills, while decently powerful, isn't a high level ability or the like. I would say +4 to a bunch of skills isn't so bad, especially when you're taking away another utility ability (Alternate Form) in exchange. But like I said, I'd think about whether the party can still beat their Bluff checks, whether they can still Bluff through their Sense Motive, etc.