From Ardrana

Abjuration spells are a group of specialized protective spells. Each is used to prevent or banish some magical or nonmagical effect or creature. They are often used to provide safety in times of great danger or when attempting some other particularly dangerous spell.

Note: Abjuration as described here originally appeared in the 2nd Edition Player's Handbook for Advanced Dungeons & Dragons from TSR. Its use here is for the purposes of providing context for the campaign only.