#include "delay.h"

            simple_monster_message(monster, " appears out of thin air!",
                                   MSGCH_PLAIN, 0, DESC_CAP_A);

        {
            // Even if it doesn't interrupt an activity (the player isn't
            // delayed, the monster isn't hostile) we still want to give
            // a message.
            activity_interrupt_data ai(monster, "thin air");
            if (!interrupt_activity(AI_SEE_MONSTER, ai))
                simple_monster_message(monster, " appears out of thin air!");
        }