If you're using the KillTag, you can simply add PullRange="5" (or any number you prefer) to adjust when it 'pulls' a mob, otherwise, you'll have to modify the combat routine for general results!
If you're using the KillTag, you can simply add PullRange="5" (or any number you prefer) to adjust when it 'pulls' a mob, otherwise, you'll have to modify the combat routine for general results!