Goblet of Thralls: This goblet is carved from blackened bone or ivory with black adamantium fittings. It is the size of a large brazier, its basin in the shape of a toothed demon face, its base a nest of serpents
The first creature to splash blood into the basin when it is newly discovered is the Goblet’s attuned user. The basin can be re-attuned by not being used for a year and a day, or by being washed with holy or unholy wine.
When blood from two creatures is mixed with blood from the goblet's attuned user in a ritual that takes ten minutes to complete, a monster is created. The resulting creature is a hybrid of the blood types, often the twisted result of opposite natures being bred into humanoid form.
Nature of Creation: One of the creatures used is designated a base and one a secondary creature. The creature with the highest HD or Con score should be the base.
The creature has the creature type of the base creature if it was an outsider, dragon, fey, monstrous humanoid or giant. Otherwise, it is a monstrous humanoid. Whatever type the creature is, it has a humanoid shape.
The creature has the average HD and natural armor of its base and secondary forms, rounded down. Reduce the physical statistics as if they had been changed from large to medium creaturs. Average all stat bonuses and round them down to the nearest whole, even number. Add or subract them from ten.
The creature gains the vision and attack types of its base antecedent and the movement type of its secondary. Its humanoid form gives it two natural attacks if its base type has them, that do damage appropriate to a medium sized creature. It gains the racial skill bonuses and bonus feats of both creatures, the extraordinary abilities of both creatures, and one supernatural or spell like ability from either contributor, chosen by highest DC or caster level.
Saves, skill points, difficulty checks, and feats are determined by base creature type and ability modifiers, with skills and feats being selected from among its base creatures by the GM, excepting knowledge skills. Probably, skills and feats used by both creatures will surface first.
Initial reaction: If the user of the goblet of thralls does not have the leadership skill, the creature that results from use of the goblet has an alignment that uses its secondry's law/chaos axis and its base's good/evil axis. If it shares one axis with the goblet’s user, is begins with an attitude of unfriendly. If it shares two axis, it begins as indifferent. Otherwise it starts as hostile.
Changing the creature’s attitude to friendly or helpful will get its help, but if asked to do something against it’s alignment, it will revert to its former attitude.
If the user has the leadership feat, the creature will have their alignment and react to them as if they were a second cohort as long as the total of its hit dice are less than the user’s cohort level allowed by the user’s Leadership Score. The user of the goblet will not gain additional lesser cohorts from using the goblet. Additional creatures created by the same user will start out with an attitude assigned using the method above.
For instance: Fievrag, an evil high priest of darkness, takes blood from the giant eagle cohort of his good nemesis, which he has captured, and a choker living in the old dungeon that serves as his secret lab, to create a creature that he thinks will be both terrifying and physically imposing.
The GM rules that since the eagle has higher hit dice, it is the base creature.
The giant eagle is a large magical beast with 4 HD, +3 natural armor bonus modified to +1 for being reduced to medium size, +8 Str, +6 Dex, Con +2, Wis +4 bonuses modified to +0, +8, -2 Con for going from large to medium, a fly speed, claw attacks, a low light vision, and neutral good alignment.
The choker is a small aberration with 3 HD, +2 natural armor bonus, +6 Str, +4 Dex, +2 Con, -6 Int, +2 Wis, -2 Cha, modified to +10 Str, +2 Dex, +4 Con for going from small to medium, a climbing speed, tentacle attack, darkvision, and chaotic evil alignment.
The new creature’s type is monstrous humanoid. It has 3 HD, a +2 natural armor bonus, +8 Str, +4 Dex, +2 Con, -2 Int, and +2 Wis bonuses, low light vision and flight, and 2 tentacle attacks. It begins with 3 skill points, and three feats (one bonus) and a neutral evil alignment. It has the evasion, improved grab, and constrict extraordinary abilities.
The GM puts the skill points into Listen +1 (+1), Spot +1 (+5), and Hide +1. He assigns the Flyby Attack, Improved Initiative, and Lightning Reflexes feats.
The new creature has an alignment one step from its maker and so is indifferent to him. With a successful diplomacy check, Fiervag convinces the creature to guard the dungeon exit to his lair from intruders or escapees. If Fiervag asked him to hold off killing an escapee, however, he would return to indifferent and need to be re-convinced. If Fiervag botched his diplomacy check, the creature might very well attack Fiervag.
Strong transmutation; CL 9; Create wondrous item, baleful polymorph; 72,000 gp.
NPC Gear: 19th
Treasure Value: 20th
I valued this as if it were a magic item version of the Leadership feat. Essentially, the goblet is a baroque was of doubling the leadership feat. Otherwise, its a weird NPC generator. I value feats as 1+any requirements, the five levels required to take leadership being the requirements. So:
Notes: Despite it's high value, you can use this device at any point in a campaign. Nobody will have the gold to buy it. Governments or organizations who might would be inclided to take the item. A generous government would give the PCs a reward equal to a treasure of the party's level. In the posession of either a PC or NPC, the Goblet's value is limited by which creatures that character can defeat, and modified by the fact that they must mollify strong creatures.
In fact, if PCs own the goblet of thralls at low levels, it will probably be more trouble than its worth to protect it from other people.
If PCs make particularly clever use of it (creating and charming muscley thralls). You can also control the Goblet's use by awarding XP to thralls that aren't controlled by the leadership feat.
You can limit the efficacy by insisting that blood used must be fresh, from a living creature.