More than any previous edition of Dungeons & Dragons (D&D), 4th edition focuses primarily on party dynamics, rather than individual achievement. This new focus shows in the new character class role designations, as well as monster design, characters abilities, and suggested encounter design. Due to the new focus, creating a character in 4th edition D&D is more of a group endeavor than it was in previous editions. In fact, it is usually best to build the party as a group, rather than to build characters individually.
When building a party in 4th edition D&D, you usually want to build a balanced party. A balanced party is one that can adequately operate in just about any given situation, both during combat and outside of combat. In general, a balanced party will not be specialized against any specific types of threats or challenges, but individual characters in the party will often be specialized.
Two types of encounters need to be considered when building a balanced party: combat encounters and non-combat encounters. Combat encounters will test the combat abilities, tactics, and combat synergies of your characters. Non-combat encounters will usually test the skills of your characters and possibly the special features of your characters’ classes.
The most important rule for being balanced for combat is to have at least one character in your party that covers each of the four major roles: defender, striker, leader, and controller. Each role has at least five classes designated as that role, which provides a lot of choice in character classes. In addition, most characters tend to have a secondary role. If at all possible, you also want the four roles to be covered by at least one secondary role of your characters.
Another major consideration when building a balanced party should be melee and ranged combat. If at all possible, you want approximately half your characters to be capable melee combatants and approximately half of your characters to be capable ranged combatants. Since many character classes can be capable at both ranged and melee combat, it is possible to have over half of your party capable in each. If this isn’t possible, prioritize melee over range, slightly. Also, always be certain to have at least one character that can attack at a range further than 10 squares.
The next rule for making a balanced party, in regards to combat, is creating combat synergies between your characters. For example, a cleric is very good at healing damage by allowing allies to spend healing surges. With a cleric in your party, you may want high healing surge defender like a warden in your party. If you have a low healing surge defender, like a swordmage, an artificer, that allows sharing of healing surges, may be optimal.
You do not need to consider all of the combat abilities of the characters when determining synergies between party members. Instead, consider the focus of the character and see how that focus synergizes with the focus of another character. For example, druids are particularly good at slowing, immobilizing and restraining enemies. This synergizes well with a shielding swordmages defensive abilities.
In addition to combat abilities, you should also consider non-combat abilities when building a balanced party. The main rule about non-combat abilities is that you want at least one character in the party trained in every skill in the game, preferably two characters. Thus, when choosing a character for a balanced party, avoiding overlap in trained skill is an important consideration. In the example above where your party has a powerful healing cleric, a warden is probably a better defender choice than a paladin, because they have similar combat potential, but the paladin and the cleric will have almost exactly the same trained skill set.
Once you have a framework for a balance party, you can start considering variations. For example, if none of the characters appeal to one of the players, you probably have some room to change a character, even if a little balance is lost. Perfect balance is impossible, and characters can use magic items, multiclassing, or focus on secondary roles in order to recover some lost balance. Also, if you more than four characters, often at least one character can be built without concern for balance.
With these tips, you should be able to build a 4th edition D&D party that is both balanced and enjoyable for every player at the table. As much as party balance is important in D&D, enjoyment of the game is also important. If you and all the other players are having fun, then you have built your characters well, no matter how you built them.