Saving Throws

This is pretty much straight out of D&D, so should be fairly obvious to most players.

The idea is when certain spells are cast, there is no 'hit or miss' chance, they are simply going to happen, but you then get a dice roll for a chance of saving your own ass from the majority of the damage and/or the status effect.

Successful Saving Throw Results

• Upon a successful save, damage or the spell affect may be modified:
  • Damage: Typically, per D&D, it is reduced by a percentage (1/2, 1/4, etc) and that appears to be exactly how realms works.
    • The exact result of the save is coded into that spell itself, so each spell is unique in regards to the specific modification that results from a successful saving throw.
  • Effects: Succeeding a save against a status ailment like blindness, curse, etc, can work in 2 days:
    • Status application fails: You don't get blinded
    • Status application duration modified: You don't get blinded for as long (maybe 5 rounds instead of 500)

Here are some examples that were easy to spot in the code, just to give you a general impression of how this stuff works:

Spell Name	Successful Save Result
Burning Hands	1/2 Damage
Colour Spray	1/2 Damage
Ethereal Fist	1/4 Damage
Sonic Resonance	3/4 Damage

Some have a bit more math behind them, here's one example:

Acetum Primus

Normal Damage: dam = 1.3*(2*level*number_range( 1, 4 )+7)
Saved Throw: dam = 3*dam/4

So, you always still calculate regular damage, but if you succeed the save, you do some additional math.

For Acetum, you times the regular damage by 3, but then divide by 4.... which is just a tricky way of reducing damage by 25%

(Damage of 10 would mean (3*10)/4, or 30/4, or 7.5. So... 75% damage, 25% reduction)

Types

• Save vs Poison
  • Applies to Poison spells, impacts their success rate and/or duration
  • According to 'help con', constitution affects your saving throws vs poison.
  • Game code also refers to this save as 'death' in addition to 'poison'.
  • Known 'Poison' spells that grant a saving throw: poison, venomous touch, puinsean

• Save vs Wands/Rods
  • Applies spells cast using wands/rods, impacts spell damage and/or spell effects success.
  • However... many spells could be (are) coded to 'be' this attack type without really requiring an item, so many unknowns here.
  • Known 'Wand' based spells that grant a saving throw: weaken.

• Save vs Paralysis
  • Applies to paralysis spells, impacts their success rate.
  • Also referred to as 'Petrification' in game application occasionally.
  • Known 'Paralysis' spells that grant a saving throw: stun, gaze, immobilize.

• Save vs Breath
  • Applies to Breath attacks, impact their damage.
  • Breath attacks also damage containers and can frequently scrap them if successful.
  • Known 'Breath' spells that grant a saving throw: gas breath, spiral blast.

• Save vs Spells/Staves
  • Applies to most spells, impacts spell damage and/or spell effects success.
  • Known 'Spells/Staves' attacks: Quantum Spike, Acid Blast, Blindness, Curse, etc.

The Code

In terms of realms code, all we can do is look at the old Smaug 1.8 code and see how that works, and infer the current code works on a similar system, even if slightly modified at this point. Here's a relevant snippet for Save vs. Poison, but they're all the same for the other saves as well, exact same values.

/*
 * Compute a saving throw.
 * Negative apply's make saving throw better.
 */
bool saves_poison_death( int level, CHAR_DATA *victim )
{
    int save; 

    save = 50 + ( victim->level - level - victim->saving_poison_death ) * 5;
    save = URANGE( 5, save, 95 );
    return chance( victim, save );
}

I really am no C programmer, but I work enough with code to squint and pretend it makes sense, I read that as saying:

We're going to have an integer number we call 'save'

That 'save' is defined by taking the number 50, adding (victims level - caster level - victim saving throw for X), and multiplying by 5. 

We'll limit that resulting value to between 5 and 95

We will return the chance the victim has to save -- i.e. the % or number they need to 'roll' to save themselves.

Applied Examples

• Mob level 50, player level 50 with -20 saving throw:

50 + (50 - 50 - (-20)) * 5
50 + (20) * 5 = 100 
Returns: chance: (player, 100%)  -- 100% saving throw success

• If the mob is level 54, player level 50 with -20 saving throw:

50 + (50 - 54 - (-20)) * 5
50 + (16) * 5 = 80  
Returns: chance: (player, 80%)   -- 80% saving throw chance

• If the mob is level 49, then:

50 + (50 - 49 - (-X) * 5
50 + (1 - (-X)) * 5 = 100

Solving for X then results in -19 to achieve max 100% save chance against a level 49 mob.

Since we do most fighting here at Avatar level 50, then the only factor that really changes here is just the mobs level, and we can make a simple chart showing the max "Save vs. X" number you need to reach 100% chance on a saving throw:

MoB Level: 100% save number:
       48: -18
       49: -19
       50: -20
       51: -21
       52: -22
       53: -23
       54: -24

Conclusions

Realms Saving Throws work exactly like D&D

Not all spells/attacks grant a saving throw opportunity. Those that do are specifically coded with a unique damage modifier.

This code outputs your percentage of succeeding a saving throw. I don't really know how that is then rolled/calculated, but since its a percentage it shouldn't really matter. In D&D terms, 80% saving throw chance would just mean rolling a d20 and getting a 5 or higher. I'm assuming that one way or the other realms is doing similar math and simulated 'rolls'.

In situations where a mob launches an attack that grants a saving throw, you can significantly reduce the damage you eat by having a high saving throw.

Damage still stacks with Sanctuary, Protection, Resists, etc. When 'saved' against, a spell that would normally do 100 damage may instead send 50 damage to the player. The player's spells then further reduce damage. Sanctuary would drop that 50 to 25. If the mob is evil and you have protection, the result is 18.75 damage received.

Maximum Saving Throw Value

At least in Smaug 1.8, and given I have never seen a mob higher than level 54, having a Save Vs. X of 24 is the max you would ever need for 100% success.

Spells Impacting Saving Throws

Most of the spells you can cast that impact saves are based on Class. There are not a ton of options out there for general usage by any class.

To impair a mob's saving throws, Nephandi Spells are the primary class of interest.

To buff your own saving throws, Clerics 'bless' is a standard castable spell, otherwise Rangers/Druids are required and can only buff themselves.

Save vs.	Buff	DeBuff
Poison	-	kleshas, mental anguish
Rod	forest prayer	kleshas
Paralysis	-	kleshas, mental anguish
Breath	-	kleshas
Spell	bless, minor invocation, forest prayer, ritual blessing, oaken consecration, minor invocation	kleshas, ceangail nadur, curse, vomica pravus

Integration with Resistance/Immune/Susceptible

There's also code that modifies saving throws based on Resistances/Immunities/Susceptibilities ("RIS"), written by the man himself.

This just seems to be a nice little common sense modifier where if you are imm/res/sus to X, you get a big bonus, small bonus, or penalty, to your saving throw chance. You can try to work out the exact values in the code block below, I'm satisfied to just get the gist of the idea at this point.

RIS & Saving Throws:

• For some spells, there is both RIS and also a Saving Throw.
  • For example, "Fire" is a damage type defined within RIS, and there may be a spell 'Fire Breath' which offers a Saving throw (vs. Breath)
• Saving Throw would be rolled (if you are resistant, you get a bonus) and upon successful save the damage is decreased per spell specific code (lets say 1/2)
• Resistances are applied, if you are 10% Resist Fire, that chance of success is then further reduced by 10%.

• Note that 'immune' is a status really only pertains to mobs (who can be immune slashing, or fire, or whatever).
  • There are not many player spells that make us immune to stuff. The most obvious one is Mage's "Invoila Magicka" which makes you immune magic, but then makes saving throws fully moot anyhow as you would be immune the damage regardless of saving throw success or not.

/*
 * Make adjustments to saving throw based in RIS                -Thoric
 */
int ris_save( CHAR_DATA *ch, int chance, int ris )
{
   sh_int modifier;

   modifier = 10;
   if (IS_SET (ch->immune, ris) || IS_SET (ch->stance_immune, ris))
     modifier -= 10;
   if (IS_SET (ch->resistant, ris) || IS_SET (ch->stance_immune, ris))
     modifier -= 2;
   if ( IS_SET(ch->susceptible, ris ) || IS_SET ( ch->stance_immune, ris))
   {
        if ( IS_NPC( ch )
        &&   IS_SET( ch->immune, ris ) )
          modifier += 0;
        else
          modifier += 2;
   }
   if ( modifier <= 0 )
        return 1000;
   if ( modifier == 10 )
        return chance;
   return (chance * modifier) / 10;
}