There are three types of spells: spirit magic, divine magic, and sorcery. Spirit magic is akin to the spells used by the spirits a shaman controls, divine magic is a reflection of a deity's power, and sorcery uses the caster's innate power to manipulate the natural world. Some people may use other forms of magic. For example, dragonewts use dragon magic. These exotic magics are left to the gamemaster.
Many spells which affect an unwilling target do not automatically do so. The target's resistance must be overcome. This is done by winning an opposed roll of the caster's POW, against the target's POW. Unless the spell caster wins, the spell has no effect on the target. If the caster wins, the spell does affect the target.
Divine magic takes effect at the beginning of the round it's cast. Other spells don't usually take effect until the end of the round. If the caster wants the spell to take effect before some other action, he must win an opposed DEX roll. [Option: DEX is reduced by the magic points in the spell.]
Example: Suboti wants to cast Demoralize on an attacking troll. Suboti wins a DEX contest with the troll, and gets to cast the spell before the attack is resolved. If she'd lost, the spell would affect the troll after the resolution.
Casting spells takes time, and larger spells take longer. Normally, casting a spell takes a number of rounds equal to the points of the spell (but not counting magic points used to boost a spell). The following modifiers apply to casting in less or more time:
NOTE: Spell descriptions are derived from RuneQuest4 and Gods of Glorantha. If a spell is not described here, it works as it does in those sources.