Steel Shadow

Seldom seen outside its metal shell, a steel shadow resembles a giant flatworm at ease on land or in water. Metal objects are its home and its arsenal. The only sign of its presence is a dark stain or shadow on the metal's surface, which gives the creature its name. It can dwell within metal forever and peers out through it with 80-foot infravision.

Two barbel-like feelers dangle harmlessly from its mouth, but its stretchy body holds five retractable, barbed, blood-sucking tentacles that reach up to six feet. A tentacle that hits deals 2-5 per round automatically until the shadow pulls it back or someone cuts it off; each tentacle is AC 7, and 6 points in one go will cut it off.

Entering or leaving metal costs it a full round at AC 7 with no physical attacks. It can enter any metal object bulkier than a longsword, such as a shield, armor, or battle axe, but not items carrying enchantments like magical blades or armor. While inside, it is AC 2 and shares in any attack on the metal: physical blows do it half damage, a successful save by the metal protects it entirely, and if the metal fails its save the shadow gets its own. Disintegrating the metal ejects the shadow unharmed. If the metal is being worn, all its tentacles hit automatically the round after it merges.

Any metal it touches can be brought to life to fly, crawl, or fight. Weapons it wields deal their usual damage at the shadow's THAC0, while a shield or whole suit of armor moves as one piece and rams for 1d4+1. Crawling along a floor or ledge, it can launch metal-tipped arrows or fling loose coins; a handful of coins deals 1 point, can tip over light objects, and forces fragile items to save. Animated missiles have 10/20/30-foot ranges with the usual penalties. Items keep pace with the shadow when it rides along or when they outsize it, and otherwise move at MV 21. These animated attacks come on top of its own.

It loves to stand up a hollow suit of armor, or one with bones or a body still inside, so enemies mistake it for undead, then stagger forward and seize a human in a metal embrace. Tentacles burst from the helm at the victim's face. Each round both sides roll a d20, and the prey escapes only by rolling higher; otherwise the grip holds another round. The DM decides which weapons and spells a held character can use.

Steel shadows can live anywhere metal is found, from shipwrecks on the sea floor to ancient tombs sealed in mountain glaciers.

Electrical attacks, including lightning, do not affect them. Heat metal cast on a shadow's metal home heals it by the amount of damage the spell would normally deal. A rust monster's touch on occupied metal forces the shadow out immediately and deals it 4d6 per hitting tentacle, though once free it is safe from further rust monster contact.

Its ichor goes into potions, inks, and enchantments for animating, heating, or passing through metal, and treated skin wards against lightning and energy damage.