No really, it isn’t

Game Mechanics

Attack-like actions

If you’re trying to inflict hurt upon another person, critter, inanimate object, or abstract notion in the D&D system (d20 system, whatever) there are two ways this will happen:

• Make An Attack Roll

  Everything has an AC of some kind, just roll a d20 and add the pertinent bonuses. They’re on the character sheet. A 6th level fighter with a 12 strength and a +2 longsword rolls a d20 die (cuz that’s just how these things are done) plus 6 for being a 6th level fighter, 1 for having a 12 strength, and another 2 for his nifty sword.

• The target makes a saving throw

  in the event that you have something along the lines of a Fireball spell or another attack means that affects an area, everybody that would normally get hit gets to make a saving throw. This too is on the character sheet (d20 + base + modifiers).

As a result, there is almost always some degree of randomness in any dealing-out of damage. Only a very small number of attack actions have no such margin for error, such as Magic Missile (which makes up for its poor damage output).

Opposed Checks

Sometimes, such as when grappling, both the subject and the object of an action need to roll. This normally happens when whatever you’re doing forces your opponent to do the same thing. In the case of grappling, starting it up requires an attack roll. Maintaining or furthering the grapple one way or another requires an opposed check. Both participants roll a d20, add in their pertinent stats and other modifiers (as determined by the DM) and away you go.

Experience

Your DM determines how you get XP, when you get it, and how much you end up with. That’s his business. Don’t sweat it. If you think you aren’t leveling quickly enough, talk to your DM. There may be a real reason for it.

Magic Items

Every magic item functions exactly as described by the DM. A typical DM will use descriptions from source material such as the DMG or a game supplement. It is recommended that custom items be recorded in some way so that everybody can remember how the darned thing works.

Stacking

Understanding stacking is about 3/4 of the D&D learning curve. Attack rolls, saving throws, skill checks, damage rolls, and just about anything else that involves throwing some dice around will possibly involve some stacking of some type.

Generally speaking, to determine the success of an action you roll a d20 plus the relevant bonuses, minus the relevant penalties. There are a number of means to get additional bonuses.

You average D&D character is born with an AC of 10. This is an easy target, so something should be done about this to assure the survival of a character. Armor is a common means of doing this, ranging from the +1 armor bonus of a suit of padded armor to the +8 armor bonus of a set of Full Plate armor. Stack on top of this enhancement bonuses, deflection bonuses, luck bonuses, and so forth, and you can end up with a rather impressive AC that’ll keep even an accomplished Fighter scratching his head.

So why not put on two sets of Full Plate and get a +16 armor bonus to your AC?

You don’t get the same kind of bonus twice. This means that you can’t cast Bull’s Strength on yourself repeatedly until you’re stronger than Hercules. If you want to get a particular benefit more than once, you’ll have to go to multiple sources. Common types of bonuses are:

• Armor Bonus
• Morale Bonus
• Competence Bonus
• Deflection Bonus
• Inherent Bonus
• Racial Bonus
• Enhancement Bonus
• Circumstantial Bonus

When looking at spell descriptions, magic items, or special class/racial abilities, any bonuses to a skill or check will have a description of the type of bonus it is.

For Example, from the DMG a Belt of Giant Strength offers a +4 or +6 “enhancement” bonus to the wearer’s Strength attribute. The spell Bull’s Strength grants the target a 1d4+1 “enhancement” bonus to the wearer’s Strength Attribute. They don’t stack. Somebody under the influence of both of these effect only gains the better of the two.

Saves vs. Checks

A Check (rolling d20 + relevant attribute + relevant skill) is to actively do something. If there is no skill that a character has to let him pro-actively accomplish something, he gets to try based purely upon his relevant attribute. Sometimes a DM will rule that a given task cannot have a skill added to it (such as a Strength check to open a jammed door: strictly a matter of strength, not skill).

A Save (rolling d20 + relevant attribute + base save bonus) is to avoid something reactively.

For example: if a pit trap opens beneath you, avoiding falling to your death is a Reflex Save. Having accomplished this, jumping over the pit is a Jump Check.

Similarly, resisting a magical compulsion to jump off a bridge is a Willpower Save whereas determining whether a shopkeeper is trying to pull a fast one on you is a Sense Motive Check.