Crypt of Decay Alternative Access (Plane of Disease)
This quest requires you to collect 4 different types of Larvae Flesh from enemies in the Plane of Disease and bring them to Grimror Plaguebringer. Successfully completing this task will grant you an alternative means of accessing Crypt of Decay, normally you're required to defeat Grummus.
The four items that you need to bring to Grimror Plaguebringer are Generian Larvae Flesh, Harrion Larvae Flesh, Scaevian Larvae Flesh, Sengian Larvae Flesh. All four of them drop from different named Larvae found around the zone. The Larvae that drop the flesh share a similar name, IE Harrion Larvae Flesh is dropped by Harrion Larvae so you'll only need to hunt specific ones.
Harrion Larvae - PH is Malarian Larvae
Sengian Larvae - PH is Tachnian Caterpillar
Scaevian Larvae - PH is Tsetsian Pupa
Generian Larvae - PH is Planarian Larvae
You'll need to hunt the place holder enemies I have listed above in order to get the named larvae to spawn. The named Larvae have a 50% chance of dropping the flesh that we're after - at least according to Allakhazam they do. Use my map below if you don't know the locations that you're supposed to hunt to gather the larvae.
Here's a picture of all four different types of Larvae that we're after.
Once you hand in all four of the Larvae to Grimror your entire group will be rewarded with the key to the Crypt of Decay. Also, the person who turns in the Larvae will be given a Bracer that allows you to cast Resist Disease onto your target.