wait for the warrens to come out.
Kill kobolds in the warrens with aoe/ae
this is the best way
edit:
https://wiki.project1999.com/Heretics
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I never tell anyone to kill Sentinel's in erudin. In my mind it doesn't behoove anyone on p99 to ruin their erudin faction for paineel, when you can easily have both.
Some people don't care about erudin faction because they never go there but it adds something to your character if you're liked everywhere in my opinion.