Okay, recently I was asked to join in on a Old World of Darkness game. I picked out a race that I was told about that sounded quite interesting. The only problem is that no one really knows anything about them, or a book that I can find anything out about them either. Does anyone know a book that there in or anything that I can point me in a direction more than, "Oh they're cool!"
The only good place to find information on the Tlacique (that is, more than just a brief mention) is in the revised Followers of Set Clanbook.
More specifics on their special type of sorcery can be found in the Blood Sacrifice: Thaumaturgy companion.
Essentially, the clanbook has all the lore and game information for the bloodline, while the thaumaturgy book focuses on fleshing out their special magic.
You can find a little of info in the WoD wikis:
But to understand what Tlacique are, you you should read the basic description of the Followers of Set, since they are a bloodline that split from them.