Demon Wraiths!
[CREATURE:WRAITH_DEMON]
[NAME:wraith demon:wraith demons:demonic]
[TILE:'&'][COLOR:4:0:1]
[SPEED:600]
[MODVALUE:50]
[FANCIFUL]
[FIREBREATH][FIREIMMUNE][LIKES_FIGHTING][MAGMA_VISION]
[FLIER]
[LOCKPICKER][TRAPAVOID][INTELLIGENT]
[GENPOWER:5]
[BLOODTYPE:0]
[EVIL]
[BUILDINGDESTROYER:2]
[NOFEAR][NOEXERT][NOBLEED]
[NOPAIN][EXTRAVISION][NOTHOUGHT][NOBREATHE][NOSTUN][NONAUSEA]
[NOSTUCKINS][NOMEAT]
[CANOPENDOORS]
[DAMBLOCK:10]
[PREFSTRING:smokelike bodies and blackened bones]
[PREFSTRING:unique brimstone scent]
[PREFSTRING:scorching attributes]
[PREFSTRING:wicked, shameless ego]
[BODY:HUMANOID:TAIL:2EYES:2EARS:2WINGS:NOSE:HEART:HUMANOID_JOINTS:5FINGERS:5TOES]
[SIZE:14]
[CHILD:12][BABY:1]
[ATTACK:MAIN:BYTYPE:MOUTH:bite:bites:8:10:BURN][ATTACKFLAG_CANLATCH]
[ATTACK:SECOND:BYTYPE:GRASP:punch:punches:4:8:PIERCE][ATTACKFLAG_WITH]
[NO_DRINK][NO_EAT][NO_SLEEP]
[EQUIPS]
[FAT:0]
[ALL_ACTIVE]
[STANDARD_FLESH]
[FIXED_TEMP:10005]
[SWIMS_INNATE][SWIM_SPEED:2500]
[PERSONALITY:ANXIETY:0:0:0]
[PERSONALITY:DEPRESSION:0:0:0]
[PERSONALITY:SELF_CONSCIOUSNESS:0:0:0]
[PERSONALITY:VULNERABILITY:0:0:0]
[PERSONALITY:FRIENDLINESS:0:0:0]
[PERSONALITY:ASSERTIVENESS:100:100:100]
[PERSONALITY:CHEERFULNESS:0:0:0]
[PERSONALITY:TRUST:0:0:0]
[PERSONALITY:STRAIGHTFORWARDNESS:0:0:0]
[PERSONALITY:ALTRUISM:0:0:0]
[PERSONALITY:COOPERATION:0:0:0]
[PERSONALITY:SYMPATHY:0:0:0]
[ENTITY:FLYING]
[CREATURE:WRAITH_DEMON]
[TRANSLATION:GOBLIN]
[WEAPON:ITEM_WEAPON_DEMON_SPEAR]
[WEAPON:ITEM_WEAPON_DEMON_BOW]
[AMMO:ITEM_AMMO_DEMON_ARROWS]
[WEAPON:ITEM_WEAPON_DEMON_SWORD]
[HELM:ITEM_HELM_VEIL_HEAD:COMMON]
[HELM:ITEM_HELM_MASK:COMMON]
[SHIELD:ITEM_SHIELD_SHIELD]
[TOY:ITEM_TOY_PUZZLEBOX]
[INSTRUMENT:ITEM_INSTRUMENT_FLUTE]
[INSTRUMENT:ITEM_INSTRUMENT_HARP]
[INSTRUMENT:ITEM_INSTRUMENT_PICCOLO]
[CLOTHING]
[CURRENCY:COPPER:1]
[CURRENCY:SILVER:5]
[CURRENCY:GOLD:15]
[SELECT_SYMBOL:WAR:NAME_WAR]
[SUBSELECT_SYMBOL:WAR:VIOLENT]
[SELECT_SYMBOL:BATTLE:NAME_BATTLE]
[SUBSELECT_SYMBOL:BATTLE:VIOLENT]
[SELECT_SYMBOL:SIEGE:NAME_SIEGE]
[SUBSELECT_SYMBOL:SIEGE:VIOLENT]
[SELECT_SYMBOL:ROAD:NAME_ROAD]
[SELECT_SYMBOL:TUNNEL:NAME_TUNNEL]
[SELECT_SYMBOL:BRIDGE:NAME_BRIDGE]
[SELECT_SYMBOL:WALL:NAME_WALL]
[SELECT_SYMBOL:REMAINING:EVIL]
[CULL_SYMBOL:ALL:DOMESTIC]
[CULL_SYMBOL:ALL:FLOWERY]
[CULL_SYMBOL:ALL:HOLY]
[CULL_SYMBOL:ALL:PEACE]
[CULL_SYMBOL:ALL:NEGATOR]
[CULL_SYMBOL:ALL:GOOD]
[INVADERS_IGNORE_NEUTRALS]
[AT_PEACE_WITH_WILDLIFE]
[USE_ANIMAL_PRODUCTS]
[USE_MISC_PROCESSED_WOOD_PRODUCTS]
[EQUIPMENT_IMPROVEMENTS]
[ABUSE_BODIES]
[SPHERE_ALIGNMENT:WAR:512]
[ART_FACET_MODIFIER:GOOD:0]
[ART_FACET_MODIFIER:EVIL:512]
[FRIENDLY_COLOR:5:0:1]
[DEFAULT_SITE_TYPE:CAVE]
[LIKES_SITE:CAVE]
[TOLERATES_SITE:CAVE]
[CAN_HAVE_MILITARY_LEADER]
[CAN_HAVE_MILITARY_SITE_LEADER]
[START_BIOME:MOUNTAIN]
[START_BIOME:NOT_FREEZING]
[BIOME_SUPPORT:ANY_WETLAND:2]
[BIOME_SUPPORT:ANY_DESERT:3]
[BIOME_SUPPORT:ANY_FOREST:3]
[BIOME_SUPPORT:ANY_LAKE:2]
[BIOME_SUPPORT:MOUNTAIN:3]
[BIOME_SUPPORT:ANY_GRASSLAND:1]
[BIOME_SUPPORT:ANY_SAVANNA:1]
[BIOME_SUPPORT:ANY_SHRUBLAND:1]
[BIOME_SUPPORT:ANY_RIVER:1]
[PROGRESS_TRIGGER_POPULATION:1]
[PROGRESS_TRIGGER_PRODUCTION:1]
[PROGRESS_TRIGGER_TRADE:1]
[ACTIVE_SEASON:SPRING]
[ACTIVE_SEASON:SUMMER]
[ACTIVE_SEASON:AUTUMN]
[ACTIVE_SEASON:WINTER]
[AMBUSHER]
[ITEM_THIEF]
[MAX_STARTING_CIV_NUMBER:100]
[START_GROUP_NUMBER:10]
[MAX_POP_NUMBER:10000]
[MAX_SITE_POP_NUMBER:120]
[RELIGION:REGIONAL_FORCE]
[WANDERER]
[SCOUT]
[BEAST_HUNTER]
[PERMITTED_JOB:MINER]
[PERMITTED_JOB:CARPENTER]
[PERMITTED_JOB:BOWYER]
[PERMITTED_JOB:WOODCUTTER]
[PERMITTED_JOB:ENGRAVER]
[PERMITTED_JOB:MASON]
[PERMITTED_JOB:ANIMAL_CARETAKER]
[PERMITTED_JOB:ANIMAL_TRAINER]
[PERMITTED_JOB:HUNTER]
[PERMITTED_JOB:TRAPPER]
[PERMITTED_JOB:ANIMAL_DISSECTOR]
[PERMITTED_JOB:FURNACE_OPERATOR]
[PERMITTED_JOB:WEAPONSMITH]
[PERMITTED_JOB:ARMORER]
[PERMITTED_JOB:BLACKSMITH]
[PERMITTED_JOB:METALCRAFTER]
[PERMITTED_JOB:GEM_CUTTER]
[PERMITTED_JOB:GEM_SETTER]
[PERMITTED_JOB:WOODCRAFTER]
[PERMITTED_JOB:STONECRAFTER]
[PERMITTED_JOB:LEATHERWORKER]
[PERMITTED_JOB:BONE_CARVER]
[PERMITTED_JOB:WEAVER]
[PERMITTED_JOB:CLOTHIER]
[PERMITTED_JOB:GLASSMAKER]
[PERMITTED_JOB:FISHERMAN]
[PERMITTED_JOB:FISH_DISSECTOR]
[PERMITTED_JOB:FISH_CLEANER]
[PERMITTED_JOB:COOK]
[PERMITTED_JOB:BUTCHER]
[PERMITTED_JOB:TANNER]
[PERMITTED_JOB:DYER]
[PERMITTED_JOB:HERBALIST]
[PERMITTED_JOB:BREWER]
[PERMITTED_JOB:LYE_MAKER]
[PERMITTED_JOB:WOOD_BURNER]
[PERMITTED_JOB:MECHANIC]
[PERMITTED_JOB:SIEGE_ENGINEER]
[PERMITTED_JOB:SIEGE_OPERATOR]
[PERMITTED_JOB:PUMP_OPERATOR]
[PERMITTED_JOB:TRADER]
[PERMITTED_JOB:ARCHITECT]
[ETHIC:KILL_ENTITY_MEMBER:PERSONAL_MATTER]
[ETHIC:KILL_NEUTRAL:ACCEPTABLE]
[ETHIC:KILL_ENEMY:ACCEPTABLE]
[ETHIC:KILL_ANIMAL:ACCEPTABLE]
[ETHIC:KILL_PLANT:ACCEPTABLE]
[ETHIC:TORTURE_AS_EXAMPLE:ACCEPTABLE]
[ETHIC:TORTURE_FOR_INFORMATION:ACCEPTABLE]
[ETHIC:TORTURE_FOR_FUN:ACCEPTABLE]
[ETHIC:TORTURE_ANIMALS:ACCEPTABLE]
[ETHIC:TREASON:PUNISH_CAPITAL]
[ETHIC:OATH_BREAKING:PERSONAL_MATTER]
[ETHIC:LYING:PERSONAL_MATTER]
[ETHIC:VANDALISM:PERSONAL_MATTER]
[ETHIC:TRESPASSING:PERSONAL_MATTER]
[ETHIC:THEFT:PERSONAL_MATTER]
[ETHIC:ASSAULT:PERSONAL_MATTER]
[ETHIC:SLAVERY:PERSONAL_MATTER]
[ETHIC:EAT_SAPIENT_OTHER:ACCEPTABLE]
[ETHIC:EAT_SAPIENT_KILL:ACCEPTABLE]
[ETHIC:MAKE_TROPHY_SAME_RACE:ACCEPTABLE]
[ETHIC:MAKE_TROPHY_SAPIENT:ACCEPTABLE]
[ETHIC:MAKE_TROPHY_ANIMAL:ACCEPTABLE]
[ITEM_WEAPON:ITEM_WEAPON_DEMON_SPEAR]
[NAME:spear:spears]
[ADJECTIVE:demonic]
[DAMAGE:280:PIERCE]
[WEIGHT:45]
[SKILL:SPEAR]
[CRIT_BOOST:4]
[TWO_HANDED:10]
[MINIMUM_SIZE:10]
[MATERIAL_SIZE:5]
[ITEM_WEAPON:ITEM_WEAPON_DEMON_BOW]
[NAME:bow:bows]
[ADJECTIVE:demonic]
[DAMAGE:80:BLUDGEON]
[WEIGHT:15]
[SKILL:SWORD]
[RANGED:BOW:DEMON_ARROW]
[TWO_HANDED:0]
[MINIMUM_SIZE:10]
[MATERIAL_SIZE:3]
[ITEM_WEAPON:ITEM_WEAPON_DEMON_SWORD]
[NAME:sword:swords]
[ADJECTIVE:demonic]
[DAMAGE:340:SLASH]
[WEIGHT:45]
[SKILL:SWORD]
[CRIT_BOOST:1]
[TWO_HANDED:11]
[MINIMUM_SIZE:11]
[MATERIAL_SIZE:5]
[ITEM_AMMO:ITEM_AMMO_DEMON_ARROWS]
[NAME:arrow:arrows]
[ADJECTIVE:demonic]
[CLASS:DEMON_ARROW]
[DAMAGE:200:PIERCE]
Completely untested, but it should all work.
My initial thoughts? They might be a bit too powerful, if everything works the way that I want it to. They should show up early and sneaking, avoid de-sneaking for wildlife and then, once discovered, completely wreck the fortress. Or possibly just kill everything on their way to the thing they were trying to steal, and then leave. Either way, even the thieves should leave a trail of burning destruction in their wake. Eventually, they will start ambushing and sieging too (FUN!). I felt like it would be better to make them more difficult to start with, and then tone them down, rather than the other way around.
Their stats are taken mostly from the HFS demons, with the addition of a few weapons and DAMBLOCK equivalent to wearing platemail (they shouldn't wear other armor, though). They are fast by default (to counter slow sneaking speeds), so once they show themselves they should be very fast indeed. They have fixedtemp, so they shouldn't have issues with lighting themselves on fire (though they may have trouble swimming through magma, since they are fixed at water freezing temperature.). They also have the tags to not be slowed down by dwarves hitting them with things, so they should be nearly-unstoppable killing machines.
Dealing with them would seem to involve sealing EVERYTHING until you had several (many) champions, and then being really, really paranoid (since by the time, they should be sending ambushes). Alternately, you might be able to kill the thieves with some clever entrance design and an auto-repeating spike trap, but that would be hard (and dangerous). The weapons would be nice to stick in weapon traps, (or in adventure mode), but should be useless otherwise. On the other hand, if you kill some you'll get a nice skull to work with.