I would consider Warlock an advanced class. Just as Bishops, and Berserkers are promotion classes in fire emblem. Mage is the baseline, and is what I am allowing as to not have people in the world over shadow the level 1 heroes.

His story is also from my point of view not congruous with the story we're trying to tell here. Those influenced by Eldritch abominations, and evil creatures are not something that we should have traveling with the party, nor does what his character backstory lead me to believe he'd have any intentions, or plausible reason other than to bring chaos into the group. He neither fits the current aesthetic, nor does his backstory, from my knowledge, have any backing from the canon which to my knowledge has monsters, and evil beings but no background that suggests that primordial evil lovecraftian gods exist. 

In short the character neither has a plausible reason to have the kind of 'godly', and or primordial influences that caused half his backstory, nor does his backstory suggest he would be level 10 with that kind of knowledge. And even overlooking both of those he does not fit into the setting that I would like for this roleplay as such I am rejecting the character. [@Bright_Ops]