Recently, I posited a couple of thought experiments. One of the more interesting comments was from Anthony who reminded me of the career system from WFRP. That got me to thinking if something could be tacked onto an older system of D&D.
Jeff Rients and Beedo, among others have pointed out that there is plenty of textual evidence to support the idea that the first several levels of character development are apprenticeship levels. In addition, around 4th level characters move beyond being an apprentice to some kind of hero status. Herein I see a means for understanding and implementing the concept of the prestige class. [BTW I am going to go human-centric here, but the concept is easily applied to demi-humans and demi-human classes.]
All characters begin the game with one of the basic three (four) classes. The first three levels are apprenticeship/proving ground levels. Those that survive and prove their worth then embark on one of several career paths depending upon the campaign, what has become available to them and player desire. The most obvious path is the class as written; however, if the character is willing to make a trade-off in powers/abilities/obligations for other class abilities, they can chose what amounts to a prestige class. They continue to advance as their original class in terms of XP requirements. Here are some for instances for each class:
ClericOne interpretation of the normal class progression of the cleric is ordination. Prior to gaining 4th level, clerics are alcolytes — trainees trying to decide whether or not ordination is their path. Alternative career paths for cleric characters could represent choices made by those who decide either not to get ordained or ordained into a specific order/ministry. For example, one could become a Healer.
Disadvantage: Healers do not improve in their ability to Turn Undead beyond 3rd level; Healers acquire spells as a cleric one level lower (no new spells are gained at 4th level; at 5th level, they gain spells as a 4th level cleric).
Abilities: Healers may Lay on Hands at 1hp/level per day; they may spontaneously use any spell slot as a cure spell (they can prepare several non-healing spells but cast them as cure spells). The efficacy of the spell must be of an equal or lesser spell level as the spell slot used.
FighterAt 4th level, fighters may choose to take the path of a Berserker.
Disadvantage: There is a 5% chance that every time a Berserker goes into a Rage that they will lose control and attack the nearest person regardless if they are friend or foe.
Abilities: In combat, a Berserker can go into a Berserker's Rage. While in a Rage, the Berserker can trade AC for a either a bonus to hit or a bonus to damage or a combination. That maximum bonus available is +4. Thus, at maximum, a Berserker could decrease their AC by 8 and gain a +4 to hit and damage. Note: this maximum is only achievable if the Berserker has the AC to give. For example, if the base AC of a Berserker is 6, the maximum number of AC they can give up for a bonus is 3 (where AC 9 = no armor).
Magic-UserAt 4th level, a magic-user may choose to take the dark path of the Necromancer.
Disadvantage: Necromancy is illegal in most civilized lands; a necromancer sacrifices a level of spell progression in order to gain the ability to Control Undead. There also may be physical signs of necromancy (pallid complexion, yellowed eyes, sunken cheeks, etc.) that get worse as the ability to Control Undead increases.
Ability: The Necromancer can Control Undead using the Turn Undead table as a 1st level cleric. As the Necromancer progresses in level, they may choose to gain more spells or gain another level on the Control Undead table.
ThiefAt 4th level, a thief may choose to pursue the path of the Assassin.
Disadvantage: The Assassin forgoes improving normal Thief abilities for each level that they wish to improve their Assassin ability.
Abilities: Assassins may use their backstab ability any time they attack from surprise (during surprise rounds as well as when using Move Silently and Hide Shadows) as well as any time they hit by 5 or more than they need. At additional levels, Assassins may sacrifice increasing their Thief skills in order to increase their backstab multiplier.
All of these can be fiddled with according the needs of a particular campaign world. In addition, there is no limit to the number of possibilities: monks, knights, paladins, battle mages, spies are just a few I can think of off the top of my head.