Currently, the guardians are the least resource intensive variant of Automaton due to lack of damage taken. Torment is highly recommended; due to the approximately 30% increase in profit/kills exceeding the cost of prayer dosage.
Players should be aware of the monster's special attack, which does a pulsing area of effect damage around the automaton at regular intervals, but roots the monster in place (note it can still perform regular auto attacks while the special is active). This can quickly do 1000+ damage if multiple pulses contact with the player.
To fight the Guardians, level 80 weaponry or better is strongly recommended; any lower will sharply cut profits. Torment and its equivalent curses, Anguish and Turmoil, significantly increase damage when fighting this monster, as the monster has high combat stats in all areas (Torment provides the correct bonus against its weakness).
Safe spotting the monster west or east of the middle area (trapping them by the walls dividing of each boss NPC during the quest) is the easiest approach, as the player takes no damage (Void Knight equipment is recommended to take advantage of this). Targeting the monsters then using Impact, Asphyxiate, or a binding spell, such as Ice Barrage, initially will root them in place for a period of time allowing the player to inflict large amounts of damage before they can approach. Impact will be ready again to bind them by the time the effect wears off effectively allowing safe spotting from anywhere in the room for those comfortable with advance combat mechanics.