The twelfth house is associated with mysticism, self-undoing and hidden enemies. Traditional astrology called this house ‘bad spirit’ and it is the joy of Saturn. The sign of Pisces is its co-significator.
“It hath signification of private enemies, of witches, great cattle – as horses, oxen, elephants ; sorrow, tribulation, imprisonments, all manner of affliction, self-undoing, and of such men as maliciously undermine their neighbours, or inform secretly against them.
It hath cosignificators Pisces and Venus; Saturn doth much joy in that house, for naturally Saturn is author of mischief; and it ruleth in man’s body the feet. In colour it presents the green. It’s a cadent house, feminine, and vulgarly sometimes called cataphora, as all cadent houses may be”William Lilly