Your zombie pet attacks count as dark element, killing a small number does take time but bokor plague doctor is all around great never had too much of an issue with small groups.
One thing to be wary of is zombie management against bosses, bokor plague doctor means you specialize in zombie damage sharpening your specialty into a focus but your weaknesses is made even more apparent whilst it is not a bad thing this ultimately is a double edge sword. Please allow me to clarify, you rely almost solely on your zombies for damage bar debuffs and incinerate combo. Against demon bosses that are resistant to dark and when you cannot replenish your zombie army as quick as they fall, this playstyle can be frustrating so stock up on zombie capsules and grab classes to improve your zombies endurance such as priest2 for mass heal since zombies taking your allies heal tiles is a big no-no, Bokor 2 is very appealing for the expand pandemic attribute which is fantastic.
Are you an int or spirit build?