Retaliation refers to the behaviors of players and various monsters in Old School RuneScape when attacked by players or other monsters.
Monster Retaliation Edit
Almost all monsters will retaliate when attacked, except if a player is unreachable (for instance: when a player attacks the monster from greater distance than the distance a monster can perform attacks), then the monster may retreat. Usually monster have a distance check of a specific amount of tiles, that means if a player walks that amount of tiles away (starting at the tile the monster spawns), it'd rather retreat when being attacked from that distance or just stop attacking a player if so is being done vice versa.
Player retaliation Edit
A player has an option in the Combat tab to select whether or not they want to retaliate automatically or not. If Auto Retaliation has been enabled, and the Entity attacking starts to walk or run away, the procedure would be introduced where the player follows that entity and attack in the meantime (while walking or running).