In
1358 DR, a
warlock coven known as the
Toril thirteen performed a
ritual that cursed most tiefling lineages—those of demons, devils,
hags, and rakshasas, among others—with the "blood of
Asmodeus", changing their original lineage with that of the
archdevil himself. This was done to make Asmodeus a "racial god", ensuring him enough followers to attain godly powers.
[16] After the
Spellplague of
1385 DR, when Asmodeus became a god, the magic of the ritual took effect across all of
Toril and afterwards most tieflings living in the 15th century
DR were of the Asmodean lineage, all having a similar devilish appearance.
[17]