From publisher blurb:

As the name implies, the OSR Warlock is a new class for old school versions of the world's most popular fantasy role-playing. It is not the official version from third or fifth editions, but instead largely inspired by a third party supplement with some ideas of my own based on the warlock from my favorite fantasy series.

The warlock is a character so imbued with magic that he can use it to blast his opponent with arcane bolts, replicate a limited number of spells, and manipulate objects with his mind.

Although primarily intended for first advanced edition, it also contains tables for other popular versions: original edition, basic and expert editions, and cyclopedic editions.