Alignments give players an idea of their characters' moral outlook. There are some lines that people simply will not cross, while others will do whatever it takes to achieve an end - and anyone can decide to do something they'll regret later. Alignments aren't simply divided between notions of good and evil, but also between order and chaos, with space in between for neutrality. A character chooses one option from both groups (such as lawful good or neutral evil), and the player is expected to keep both aspects in mind while they play. Characters interact with each other based on their outlooks, and some strife is expected. If a chaotic evil character insists on a gruesome murder in front of a lawful good character, they should be at odds. Traditionally, alignment is determined during character creation and remains the same throughout most of a campaign. Alignments can change as a character's worldview and patterns of conduct shift, but major changes usually take time.
The Player's Handbook offers guidance about how alignments should be portrayed and how they affect characters in-game, but ultimately, they're open to interpretation, and the final say rests with the DM. As a result, the alignment system is a constant source of debate in the D&D community. Some DMs choose not to use it at all, while others only bring it up for extreme behaviors. If you're new to D&D and/or to a group, you should ask the DM how they feel about alignment, if they intend to use it, and how strict their interpretations will probably be.
Alignment has been hard-baked into D&D's mechanics in a few different ways. If you're playing in a game that uses this morality system, you should be aware of a few things. Religious character types - like clerics and paladins - can lose their powers if their gods find their actions out of line. So if you're going to play a cleric, you'll want to read about the different gods available and choose one in line with how you want to play your character. Some magical spells are tied to good, evil, law, or chaos; for instance, the protection from evil spell protects someone from attacks by an evil foe. To use these spells well, you have to figure out the alignments of your targets first.
Traditionally, different fantasy races have been assigned alignments to represent their predominant culture's values. This makes it easier for characters to assume who their enemies are. If you bump into a dark elf (drow), they're probably evil, so you can expect your protection from evil spell to work on them. This shortcut has been called into question for some major reasons and not all DMs use it. As a new player, find out is if your DM is going to use racial alignments so you can adjust accordingly.
Character alignments are as follows (all explanations are my own; your opinions may vary):
Lawful good: (a.k.a. "goody little two shoes") If you have watched movies or read books, you have seen a lawful good character. Most often main protagonists are lawful good - the hero who upholds the law and protects the people can be found everywhere. A lawful good character respects law and authority and cherishes life and justice. A LG character wants good to be done and will often take action to see that it happens. LG characters are compassionate and they can't stand for the guilty to walk free.
Neutral good: NG characters care that good is done and the rest is just details. If the monarchy is good and just, the NG character will support it. If the social order is corrupt and harmful, a NG character will not hesitate to help in its overthrow. The vehicle is not important; the end result must be that good is done and balance is achieved. While others squabble over rules or argue for freedom, NG folks move past the noise and into action because goodness is what is at stake for them.
Chaotic good: CG good characters value personal freedom above the law and do not like to be interfered with. They are highly individualistic and they make their own way. They try to get ahead in life but not at any price. They value the good of others as well as their own. They can be unpredictable but are not out to backstab others.
Lawful neutral: LN characters value the letter of the law. They tend to follow internal codes of conduct or strong governments. They do not care much if the order in the land is enforced with violence. They believe in balance in the law and in their own lives. They will reward harm with harm and often take jobs as government enforcers.
True Neutral: Most neutral characters do not stick their necks out for others. They don't feel compelled to enforce good, nor do they care enough for evil. Some N characters don't know enough about the law to condone it. Other N characters don't care to be bothered about what's good, right, or wrong. They want to be left to their own devices.
Chaotic neutral: A CN character is out for himself first and foremost. He values his own freedom and leaves others to fend for themselves. A CN is a rebel, whose only cause is himself. They are unpredictable in their behavior. They will backstab a friend if it is worth it and if they can avoid punishment. They will fraternize with whomever suits them. Only if it puts them in personal danger or affects them will they try to stop an evil deed.
Lawful evil: LE characters depend on order. LE characters follow their own code of conduct and have their own internal sense of order, which they can then impose on others. They may follow the laws of the land in order to better their own position or because those laws are in harmony with their own sense of how the world should be. Many LE characters know the laws as well as judges and bend them whenever they can. They have no qualm with committing the deeds that their code allows them: murder, sabotage, deceit, slavery. They use rules and logic to protect themselves from others and to justify their own actions. They pursue power with subtlety and can be very effective rulers.
Neutral evil: NE characters will do whatever they can to get what they want. They have little respect for the law and yet they do respect what getting caught can mean to them. They are not suicidal and they are not stupid. They exploit the weaknesses in social order as well as in social chaos and get away with murder where they can. They will betray anyone if it suits them and their betrayals are likely to involve death and pain.
Chaotic evil: A CE character is brutal, greedy, cruel and lethal. Such a character follows their whims and twisted desires. They are unpredictable at best and completely insane at worst. They are very commonly seen as villains in movies and books as the opposite of the lawful good hero.
Skills are used to perform many actions, such as hiding, picking locks, or persuading the local guards to let you go. In the 3.5 edition of D&D (as in some other systems), skills are vital, and there is a long list of different ones to choose from. At every level, you gain skill points and have restrictions on how you can use them. Each class has a list of skills it specializes in; it costs double to raise a skill outside of that list. You can only raise a skill to a certain point before you have to wait; this limit goes up every time your character gains a level. However, skills are also used all the time, in and outside of combat, and having points in them gives you a big advantage. It's important to consider and invest in them carefully.
5th edition D&D has a much shorter list of skills and relies on raw ability checks more often. The character's basic proficiency bonus (one bonus based on level and class that applies to attacks, saving throws, and other rolls) applies to skill checks, so you don't have to place points in different skills. Your character can use tools or other abilities for bonuses, but they aren't necessary. Many specialized tasks, like picking a lock or forging a document, are covered by using your base attributes (Dexterity and Intelligence, in this example). A skill can give you an edge in succeeding at a task, but if you don't have a skill, you can rely on a raw ability check instead. For instance, if you don't have training in the Athletics skill, you can roll a Strength check and try to succeed that way. On the flip side, if your character has a skill that probably applies to a situation, you can ask the DM if you can roll your skill rather than making an ability-based roll.
In any case, skills are usually tied to different attributes. Deception has generally been based on Charisma, while Acrobatics rely on Dexterity. In 5e, sometimes a skill can be rolled with an unusual attribute because of the circumstances, but that's up to the DM. In 3.5 edition, a skill is always based on a particular attribute. Skills are generally rolled against a Difficulty Class - a number that indicates how difficult the task is to perform under the current circumstances. Sometimes, two characters are trying to beat each other to a goal, so they each roll their skill checks and compare the results; whoever scores the highest wins the conflict.
In 3.5 edition D&D, feats are a big deal, and it seems like every book introduced more of them. They're taken at set times and have set effects. Feats give a character a new ability or improve something she already has. All characters are eligible for feats and gain more at different levels, but some gain more than others. For instance, humans have access to an extra feat, and fighters are given more chances to take feats, but are sometimes restricted to a certain list. Feats allow you to make magic items, deflect arrows, and otherwise become more awesome. Feats are meant to enhance or grant new kinds of attacks, effects and abilities, and aren't usually tied to specific classes. Many feats have prerequisites the character needs to meet before taking them, however, or grant abilities that aren't useful to all character types.
In 5th edition, you have a choice to make: at certain levels, you can take attribute increases for your character, or choose feats instead. Since attribute increases affect many things, there's powerful incentive to take them. Feats offer bonuses to very specific scenarios and actions and may have prerequisities, such as the grappler feat, which gives an edge in wrestling with targets but can only be chosen and used by characters with a Strength rating of 13 or above. Since feats are so focused, they won't always be useful, and only a small selection are available in the Player's Handbook. From the start, 5e seems to put feats on the back burner. You shouldn't ignore them, since they could help your character, but you won't need to obsessively plan them out after consulting dozens of books.
Magic is a widespread feature in D&D and there are many aspects of it that a player must understand. Magical effects go beyond ordinary abilities, into the realm of extraordinary effects. Magic effects are typically brought into being through the use of spells, which are formulations used to interpret the raw energy of magic. Some spells require a certain set of words to be spoken, while others require the burning of a particular root. Magic users are able to manipulate the magical potential around them into actual effects: fireballs, mental domination, illusionary sounds and so on. Some magic users learn to manipulate this energy through books and regulated education; they bring forth magic through careful conduction of strict rituals (ie wizards). Other magic users have an intuitive grasp of the forces of magic and require only the desire to cast spells (as with sorcerers and bards). Yet other magic users are given the ability to cast spells through the grace of their gods, to be used in service of their deity (as with clerics).
Magic in D&D is divided up into two categories: divine and arcane. Divine spells are those granted by an outside force like a god, or nature. Arcane spells are those that a magic user can perform directly, through learning or intuitive manipulation. Arcane spellcasters cannot cast spells that are divine in nature and vice versa, although many spells are found in both categories. Arcane spells tend to be more combative in their effects; there are more arcane spells that cause damage than divine ones. Character class determines the type of spells a character can cast, the number of spells a magic user can perform in a day, as well as how many spells a magic user can know how to perform.
Spells are divided up several different ways, and one important way is according to level, from 0 to 9. Lower-level spells tend to be small effects with limited range and scope, while higher-level spells tend to affect reality in deeper and very impressive ways. As a magic user advances in character levels, they will be able to cast spells of higher levels. A magic user must advance as a magic user in order to gain more powerful spells, however; if a magic user chooses to branch out into the fighter class, their magical abilities will not improve. If a wizard chooses to take on levels as a cleric, their magical abilities as an arcane spellcaster will not improve, but their abilities as a divine spellcaster will advance.
Spells are also divided up into different types of effects, known as schools of magic. A spell can only belong to one school of magic. Spells that create objects are conjuration spells, while magic that creates something out of nothing is from the evocation school. There are eight schools of magic, and although a few spells belong to no school, most belong to one. You can choose to specialize in certain kinds of effects through simple spell selection (such as giving your wizard mostly charm and illusion spells).
Wizards hold all of the spells they know in a spell book; in reality, the book knows the spells and the wizard only absorbs them for a short time. A wizard can add new spells to their repertoire if they can copy the spells into their spellbook. Clerics differ in that they can choose from any of the universal cleric spells, up to the limit of the spells they can cast in a day. They pray for certain spells to be delivered into their minds by their god, and can pray for a different set of spells the next day. Bards and sorcerers are far more limited in their spell selection; they must choose the spells they know, and they know those spells for life. They can gain new spells when they go up in level, or they can swap out a spell for another one every few levels, but for the most part they are stuck with their selections. Spells can make or break combat situations, so every spellcaster much choose wisely.
Magic can be used for more than mere survival, however, since spells can be sold to those who need them. There are also ways to store magical effects inside of items: scrolls, potions, rings, amulets, weapons, and armor, for example. Some magical items can only be used by those who know how to use the type of magic in question; a cleric cannot use a scroll for a spell that is only arcane in nature. Other magical items can be used by whoever has them, like potions, or when the possessor meets certain conditions, like a password. All magical items are more expensive because of their very magical natures. The items that only spellcasters can use tend to cost less, however, than the items that anyone can use.
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