A Suggestion Spell causes the victim to folow courses of action that he or she might otherwise not choose.
The Suggestion Spell is of the Thinkamancy Discipline. It attempts to sway a victim away from a course of action deemed undesirable to the Caster, and towards a choice that is more beneficial. It is not capable of directly forcing action upon the victim, and can be very subtle. It would not force a loyal follower to betray a loved Overlord, but it might cause the victim to choose to attack an enemy Stack that was not dangerous, allowing a dangerous stack to pass and deal serious damage. It can cause the victim to lie about past events or otherwise act immorally.
The spell can be broken by the victim taking direct action against the Caster's best interests. When such a spell breaks, it can cause a backlash against the Caster, but a talented Thinkamancer can redirect that backlash back at the victim, causign damage and potentially killing the victim.