Banish
Harm + appropriate base
Banish a creature belonging to the appropriate base, or a set of related creatures possibly. For example banish undead, banish water elemental etc. Shouldn't kill the creature outright, but make it avoid you or an area. If the creature in question presses on, for example it's forced by some other controlling wizard, it's hurt or maybe even killed. Size/power of creature vs the effect could determine the outcome. Effect 1 would cause no real harm to any elemental, while an effect 3 would render lesser elemental incapacitated (if they could even be forced to approach), while more powerful elementals would only be hurt.
Which begs the question- will any summoning of sorts fit into the world? How would semi-sentient or even sentient undead/elementals/demons/whatever fit into Spellmaster?
