From afar, they are plunging their oversized arm into the ground, emerging it near the player some time later. Once emerged, the arm starts pumping toxins, dealing Poison damage to everything within roughly 10 yards like a Plagued pool. This attack lasts at least 3 seconds, and Herald cannot do anything else while channeling it. Use it to your advantage to attack the Herald while he is helpless. Being Knockbacked or disabled with the hand in the ground will cause a Herald to stop channeling the attack.