still have their promotion quests undertaken during a playthrough. Skill point system The game's skill point system affords the player an uncommon degree of liberty in further character improvement. More skills can be acquired for a character after party creation through various guilds across Enroth, but what can be learned depends on their class. While many adventuring skills, such as Repair and Merchant, are fully available to all classes, most weapon, armour and magic skills are restricted to certain character classes (i.e. Sorcerers can't use swords or plate armour), although advancement in learned skills is not restricted by class: an archer, for example, can become just as skilled at using a sword as a knight can. Each skill consists of two factors to it – Rank and Expertise, of which the latter is divided into three levels: Normal, Expert and Master. While a skill's Rank can be improved (up to a maximum of 60) by spending points earned from advancing a character in level or using special items, the amount needed to reach a new rank increases over time – a skill of Rank 2 would need 2 points to advance, but then need 3 points to advance past its new rank, then 4 points, and so forth. To improve a skill's Expertise, characters must find and gain training from a teacher of the respective skill. While there are a number of teachers available who can raise a skill to Expert and have basic pre-requisite for their training (money and a certain skill Rank), each skill has only one Master teacher; their location is known by Expert teachers, yet their pre-requisites are greater, with some requiring a character to have a stat at a certain amount, and even having gotten a class promotion. By achieving a higher level of expertise, a character can gain bonuses to complement it, such as being able to maintaining a spell's beneficial effect for much longer. Thus, a Knight who is level 20 could achieve a better expertise of Sword skill and thus become more powerful in later battles. While the skill system in The Mandate of Heaven was relaxed, in later sequels it was made considerably more restrictive in terms of expertise; although a new level was added in, a character's class restricted how high it went. Plot With the problem of the corrupt Guardian, Sheltem, finally dealt with in Might and Magic V: