Rules that people/you always forget

[Jon_Dahl]

What are some of the obscure or easy to forget rules in RPGs?
I'll start with three from D&D 3.5.

Jump :: d20srd.org

If you attempt a Jump check untrained, you land prone unless you beat the DC by 5 or more.

If you don't have ranks in Jump, you end up on your backside quite easily. Being prone is bad business.

Types & Subtypes :: d20srd.org
Horse :: d20srd.org
Goods And Services :: d20srd.org

Warhorse, heavy 400 gp —Proficient with no armor unless trained for war.

Armor for a horse (a Large nonhumanoid creature) costs four times as much as armor for a human (a Medium humanoid creature) and also weighs twice as much as the armor found on Table: Armor and Shields (see Armor for Unusual Creatures). If the barding is for a pony or other Medium mount, the cost is only double, and the weight is the same as for Medium armor worn by a humanoid. Medium or heavy barding slows a mount that wears it, as shown on the table below.

I don't about you guys, but at least in my games everybody forgets barding.
Does anyone ever attack anyone's mount? I don't know, but buying 100 gp studded leather to a 400 gp warhorse is economically wise, think of it as an insurance. The effect on AC will be considerable. Also consider the fact that war-trained animal is proficient with ALL armors ever invented. The downside is weight, of course. Also think about armored wardogs. Consult your DM.

http://www.d20srd.org/srd/spells/contagion.htm
Special Abilities :: d20srd.org

Contagion
The subject contracts a disease selected from the table, which strikes immediately (no incubation period).

Many people forget that diseases have infection-types. Slimy Doom is spread by a simple touch and Cackle Fever effectively poisons the air inside crammed up spaces such as dungeons. If you manage to infect one of the dungeon resident and they don't have access to healing magic, bad stuff will happen and it's possible to accumulate ridicolous amount of slain enemies unless a mid-level priest is used. Dicky DMs will naturally spoil the fun, but life is hard...

 

[Rhun]

Does anyone ever attack anyone's mount?

In games I run, at least where mounts are actually used, it is a common tactic of the enemies to target them.

 

[anest1s]

Spell failure from armor. I always forget this one.
And of course the player wont remember it either.

Any solutions, except hitting my head on a wall btw?

 

[Trance-Zg]

Spell failure from armor. I always forget this one.
And of course the player wont remember it either.

Any solutions, except hitting my head on a wall btw?

If you remember later in the fight you might call to reroll next successfull ASF roll, but that might also "inspire" player to cast ray of frost as his next spell

 

[WHW4]

Spell failure from armor. I always forget this one.
And of course the player wont remember it either.

Any solutions, except hitting my head on a wall btw?

I'm fairly bad at remembering things like this. I always have a scratch sheet I eyeball before I carry out my round's actions. Usually has my initiative up top in gigantic numbers and then a list of whatever ongoing effects. I'd just stick that there and try to glance at my "checklist" each round until it became second nature.

I still do this with Barbarian Rage attacks. Might be a simple +2 Atk/Dmg but it's so much easier to just look at the string of numbers as I roll and say "plus 25, plus 20."

 

[lordxaviar]

going back over combats... I find that the players and I both forget lots of attacks of opp.

 

[Rhun]

going back over combats... I find that the players and I both forget lots of attacks of opp.

This happens to me lots, too.

 

[Tovec]

After thinking on this for a bit I think most of my mistakes from forgotten rules relate to skill checks in one fashion or another. Pretty much unless its marked on my character sheet right beside the number I won't remember it.

-Remembering which skills are Trained Only, if we really really need to use them.
-Armor Check Penalties as it applies to pretty much everything except swim.
-Using armor that you are not proficient.
-Massive Damage rules once you are past level 7 (or something fairly low).
-The real difference in most armor.
-OOH, if its enhancement or enchantment type bonus when dealing with magic items (a +1 sword is which?)

That's all I can think of at the moment. I'm sure there are others but I'm not remembering them

 

[Dannyalcatraz]

going back over combats... I find that the players and I both forget lots of attacks of opp.

Heh- that's one I NEVER forget- I build a lot of high-Dex characters with Combat Reflexes. I have worn out some DMs with "That grants me an AoO..."

 

[Greenfield]

Diplomacy rules.

Most of the time the DM isn't certain what opposes Diplomacy and when, and what the results really mean.

A good roll on someone's part may be impressive, but it doesn't mean that they can get the other person to do anything they want.

As a refresher:

INFLUENCING NPC ATTITUDES
Use the table below to determine the effectiveness of Diplomacy checks (or Charisma checks) made to influence the attitude
of a nonplayer character, or wild empathy checks made to influence the attitude of an animal or magical beast.
Initial Attitude ————— New Attitude (DC to achieve)—————
Hostile Unfriendly Indifferent Friendly Helpful
Hostile Less than 20 20 25 35 50
Unfriendly Less than 5 5 15 25 40
Indifferent — Less than 1 1 15 30
Friendly — — Less than 1 1 20
Helpful — — — Less than 1 1

Attitude ....... Means ........................... Possible Actions
Hostile ......... Will take risks to hurt you .. Attack, interfere, berate, flee
Unfriendly ..... Wishes you ill .................. Mislead, gossip, avoid, watch suspiciously, insult
Indifferent .... Doesn’t much care ........... Socially expected interaction
Friendly ........ Wishes you well .............. Chat, advise, offer limited help, advocate
Helpful ......... Will take risks to help you . Protect, back up, heal, aid

Haggling is handled by Diplomacy, with a maximum price shift of 30% one way or another.

Intimidate is another skill whose rules are often forgotten. Intimidate is always an opposed roll, with Skill being opposed by a D20 + Hit Dice + Wis modifier + Any bonuses on Save v Fear.