Fiend Folio (1E) said:The tween's contact with humans on the Prime Material Plane is its adoption of a host - each tween will usually have a host, though occasionally one is without a host temporarily (after the death of its host, for instance). After several hours with a new host, a tween will gradually assume the general shape and characteristics of that host, who will appear to have a 'shadow' nearby, Once a host has been selected, a tween will remain permanently with him until he or the tween dies. In selecting a host, a tween will prefer an intelligent being, human or near-human, though they have no particular preference for player-characters. A tween will communicate telepathically with its host.
Fiend Folio (1E) said:The tween has the ability to see a few seconds into the future and is able to increase its host's luck. It is also able to move material things short distances, reacting with such speed that it can affect the movement of a weapon in melee. For example, it can move a sword so that it hits rather than misses. As a result, any character or creature with a tween 'partner' has two die rolls instead of one, whenever a die roll is called for, and may select the more advantageous of these rolls. (This applies to 'to hit* rolls, saving throws and the like).
Fiend Folio MC (2E) said:The tween has the ability to see a few seconds into the future, and may communicate this future-sight subliminally to its host. The tween is also able to move relatively light material things short distances, reacting with such speed that it can affect the movement of a weapon in melee. For example, it can reposition its host's sword so that it hits rather than misses. As a result, any character or creature with a tween "partner" gets two die rolls instead of one, whenever a die roll is called for, using the more advantageous of these rolls. This applies to all die rolls, attack rolls; damage rolls, saving throws, etc. This gives the host the appearance of being very "lucky" to any who are not aware that the character is infested with a tween.
Fiend Folio (1E) said:In contrast, while a tween has a beneficial effect on the actions of its host, it has the reverse effect on any other creature - friend or foe, human or otherwise, player-character or otherwise - within 50' of the host. Again, two die rolls are made in respect of the persons or creatures affected whenever a die roll is called for; however the less advantageous is selected.
Fiend Folio MC (2E) said:While a tween has an obvious beneficial effect on the actions of its host, it has the reverse effect on any other creature, friend or foe, within 50' of the host. While the tween appears to bestow luck upon its host, its parasitic nature absorbs luck from all those nearby. Two die rolls are made for all characters/monsters within a 50' radius whenever a die roll is called for, and the less advantageous is selected. A character, with a tween partner is therefore something of a curse to any companions, and usually ends up as, an outcast from any adventuring party who knows of his infestation.
Fiend Folio MC (2E) said:There are rumors about some magical research that has been done on the nature of tweens - more specifically on how to separate a tween from its host without the death of one or the other. A wish spell has been proven effective, and experiments have been done with combining dispel magic, remove curse, and plane shift, but thus tar the results of these experiments have been disastrous. An amulet of proof against detection and location will usually discourage a tween from infesting a character in the first place. The tween prefers to choose an intelligent host, and it cannot gauge a being's Intelligence in the presence of such an amulet.
BOZ said:We may want to give this guy something similar to what we gave the vagabond for inhabiting a host?