Shadow spiders are one of few monsters that are hidden on the player's minimap. If a player initiates combat with one, it will drain their Prayer points by half of the current amount, rounded up. If a player is in combat with them over a long period, they will continue to drain the player's Prayer at set intervals. They can never take away a player's last prayer point.
Item Quantity Rarity GE market price Looting bag 1 Uncommon (1/30) Not sold Slayer's enchantment 1 Uncommon  1,661 Mysterious emblem 1 Rare (1/127.5) 68,122