Here are some ideas, and inspiration, for how I am changing warlocks about. What do you think? I’m a bit concern that it is too good, but it has a pretty strong flair of danger I think.
“So, demons are the great secret. Common people know of their existence and know that we can commune with them - that is why they fear us so! But they do not realize the dull truth, which is that all our power derives from demons. Without their aid we are nothing but cheap conjurors and charlatans. Our single great ability is to summon them and bend them to our will. If we do it correctly they must obey us. If we make the slightest error, they fall upon us and tear us to shreds. It is a fine line we walk, boy.”
- Arthur Underwood (Jonathan Stroud, The Amulet of Samarkand)
Warlocks may only fight with a club (rod), dagger, staff, or whip…
The mark of the true warlock is their rod of bindings. This marks their station as a warlock and is the symbol of authority. Engraved upon it are names of power and symbols of fell beings. This rod is required for the warlock to perform their magic, similarly as clerics require their holy symbol. Warlocks learn and cast arcane spells as magicians of two thirds their class level…
Unlike magicians, however, warlocks do not maintain a library of spells and magical formulae. Rather, their spells are maintained by the creatures they command. Mechanically, the methods for warlocks maintaining their library and repertoire are mostly unchanged. However, should the warlock need to emergently exchange the spells in their repertoire they can do so. The warlock can dismiss the entity maintaining the knowledge of a specific spell and call up another one with a new spell from their existing library. Rather than spending the time and money to do this safely, the warlock instead spends 1 round and makes a saving throw against magic. If successful, the warlock suffers 1d6 points of damage +1 point per level of spell. If the save fails, the warlock suffers the attack of entity. This does 1d6 hit points of damage +1d6 per level of spell. If the warlock falls to zero or less hit points because of this, regardless of the success or failure of the saving throw, they suffer a penalty on the Mortal Wounds table equal to twice the level of the spell.
As warlocks have taken a (supposedly) quicker and easier path, they cannot perceive magic as magicians do. The spell detect magic is available as a first level spell… (In my campaign, detect magic is an at will ability for magicians.)