Are penalties stronger than equivalent buffs? Is a -3 to your opponent better than a +3 to yourself? If so is there a rough equivalency? Is a penalty twice as strong, three times etc?
Okay, you're running into the problem that you haven't taken the time to do probability tables (or find one). But the short version is, the storyteller d10 for Exalted is an obfuscated coinflip; if the target number was 6-10 and you didn't double 10s, you'd roll 5+ about 50% of the time and get 1 success on any of those dice. The adjustment then, is that with 7+ being a success and 10s counting as 2s, the probability is still effectively 50/50 of getting a success on a single die. Now, probabilistically, it takes 2 dice to average out 1 success- this is why Excellences are costed the way they are, 1m = 1d and 2m = 1 autosux and 1 autosux = 2d. In *practice*, it's better to assume that you need
three dice to guarantee 1 success.
So, from here, every point of difficulty, DV, penalty, is basically asking the defender to roll 2-3
more dice. A DV of 5 can be beaten by an attack roll of 10... but you really want 15+ dice just to be sure.
Now, part of why penalties
exist is that they add texture to the game environment- both as Charm powers and scene-based hazards or complications; and they exist to be mitigated by Charms as to underscore how Exalted don't suffer from petty inconveniences. Like, in an actual situation where you expect say, mortal soldiers to roll their pools, they can get likely 2-3 successes on 6 or 7d; that's fine. Remember also that their opponents likely only have a meaningful DV of 1-2.
Really, think about this- your standard mortal thug or hired mercenary likely has a dead average pool for a 'professional'. My Twilight has Dex 2, Melee 3, Specialty +3, and Defense +1, added together and /2 and +1 bonus to her post-calculated PDV; She's
not optimized at all. And her parry DV is
five. Dex 5, Melee 5 would kick her up to a base PDV of
seven.
Her Dodge DV is 3- most mortals don't even
have an effective Dodge DV, due to armor mobility penalties.
Assuming she doesn't do anything crazy like flurry, her DV is going to more or less sit at 5-6 until someone tries to do something about her DV outright like unexpected attacks or coordination. To
beat that DV, her attacker needs something like 12 dice, preferably 15-18d.
So what I'm trying to underscore here, is that every time you raise difficulty, apply an external penalty, and so on, you are either demanding the defender have a penalty negator,
or a dice pool equal to [Total Difficulty + Penalties *2 or 3].
Now, on the flipside, sometimes you WANT severe penalties, because these things exist to guide players towards niches or upsell their prowess. 2e's Durability of Oak Meditation exists primarily to underscore that an Exalt can, at least on a point-defense basis,
no sell most mortal attacks.
