Saga: Reroll vs. Skill Focus

[Chris_Nightwing]

I've been admiring the beautifully simple set of rules used for races in Saga. I know various people are Saga-ising their D&D games in anticipation of 4E. I thought some people might be interested in the number-crunching behind the two mechanics many of the races use for skills: rerolling checks and skill focus.

In the spreadsheet I've presented three scenarios: the first is someone trained in the skill, who boosts the relevant stat as often as possible and has a racial reroll, the second is someone similiarly trained and boosting the stat and has skill focus, the third is someone untrained and uninterested in boosting the stat but who has a reroll. My analysis is short and simple: skill focus massively helps you with difficult DCs and obviously improves your chances across the board, a reroll makes it almost impossible to critically fail and significantly increases your chances of critical success, but the overall effect is weaker than skill focus. I think the two abilities work well in their supposed roles: the former representing training and expertise, the latter representing a more innate ability which you are unlikely to ever screw up badly.

I'd be interested in anyone else's thoughts. The spreadsheet contains some a VBA macro to colour code some parts, if anyone is worried about security.

 

[Slife]

IIRC, skill checks don't have critical failures/successes.

About ninety percent of the time I'd go for the skill focus. There aren't many times when you need a super-high check that you won't be able to take twenty on.

 

[comrade raoul]

Yes. Here's a summary: I ran the numbers not long ago, and calculated that the expected result of a d20 rolled twice, with the highest result used, was a 13.825 (as opposed to the expected 10.5 without the reroll). Purely in terms of expected value, the reroll is worth a 3.325 bonus.

Of course, the reroll is better than that if you already mostly succeed (it drastically reduces the chance of an automatic failure), and obviously does a lot to increase the probability of a high natural result. In particular, there's a 9.025% chance of getting a natural 20 (up from 5%) and a 19% chance of getting a natural 19 or 20 (up from 10%).

Thus, a Jedi Knight using Juyo and Vapaad has a 19% chance of threatening a critical hit on his first attack roll in a round (the one that benefits from the reroll), which can be very powerful in the presence of other critical-enhancing effects (like Triple Crit or Fortune's Favor). Comparably, a Jedi Knight with Soresu who makes two Block or Deflect attempts in a given round, and who uses Sense Surroundings once as a free action, has about a 22.6% chance to get a natural 20 on at least one of those five Use the Force rolls.

 

[Elder-Basilisk]

Not being familiar with the SAGA system, it sounds like there are re-rolls that can only be used on particular skills--is that correct? If so, the usefulness seems like it would depend upon the skill in question, but that the re-roll might well be better for the skills that you would spend feats on:

Tumble: The typical character who spends a feat on tumble tumbles several times every combat and some tumble attempts will require two or three rolls even. Generally, without skill focus, however, characters still succeed on most of these. Skill focus would have the effect of making more tumble checks automatic at low levels. At mid-high levels, it would most likely not help for typical tumble checks which are automatic success anyway. From your summary of the analysis, however, it sounds like the re-roll would help more in the daring tumble situation where you are trying to do something that is still not automatic--for instance, tumbling past two enemies and then tumbling through a third enemies square at full speed.

Concentration: This is an interesting one. Characters will typically do what they can to avoid making concentration checks but a spellcaster will still probably end up making something like an average of one per combat with a DC between 15 (casting defensively) and 35 (a readied action to disrupt spellcasting from a moderately tough opponent) plus spell level. It seems to me that skill focus would help more with casting defensively, but the re-roll would be better in the situations where you try to keep concentrating on a summoning spell while being hit with a horrid wilting.

Use magic device: Another interesting one. Since the DCs are all very high, skill focus would be helpful, but the prohibition on taking 10 and the possibility of catastrophic failure both favor the re-roll.

 

[ThirdWizard]

IIRC, skill checks don't have critical failures/successes.

Not in the 1 fails, 20 succeeds sense, but there are times that if you fail by too much, you suffer a consequence, for example falling with a low climb check. It helps these situations out tremendously.

Thus, a Jedi Knight using Juyo and Vapaad has a 19% chance of threatening a critical hit on his first attack roll in a round (the one that benefits from the reroll), which can be very powerful in the presence of other critical-enhancing effects (like Triple Crit or Fortune's Favor). Comparably, a Jedi Knight with Soresu who makes two Block or Deflect attempts in a given round, and who uses Sense Surroundings once as a free action, has about a 22.6% chance to get a natural 20 on at least one of those five Use the Force rolls.

Don't you have to take the re-roll no matter what the result is? It's not the as good as rolling twice and taking the best result.

 

[comrade raoul]

Don't you have to take the re-roll no matter what the result is? It's not the as good as rolling twice and taking the best result.

Actually, some reroll-granting abilities in SWSE work like this, while others don't. Juyo is definitely one of the reroll-and-keep-the-better-result abilities.

 

[drothgery]

Don't you have to take the re-roll no matter what the result is? It's not the as good as rolling twice and taking the best result.

There are ways to get either, but most rerolls in Saga are 'you can reroll, but you have to keep the reroll'. That doesn't change the average (relative to just rolling once) if you always reroll, but it's likely that you'll only use a reroll ability if you know you failed, strongly suspect you failed, or you rolled very low, can reroll, and there are benefits to high-level success. Someone did the math on this either here or on WotC's Star Wars boards, and IIRC, rerolling on a ten or lower works out pretty close to the same as rerolling and taking the highest roll, with an average of about 13, and that's what nets the highest average.