The Unforgiven

Stratholme
From the main gate, clear the streets toward Festival Lane and Market Row without crossing the next arch during an existing pull. The Unforgiven ambush brings Vengeful Phantoms into the street. Check for Hearthsinger Forresten and Skul while travelling, but do not depend on either rare appearing. Ezra Grimm's tobacco box and the postboxes are deliberate side encounters; clear their surroundings before interacting.

The Unforgiven
Elite UndeadThe Unforgiven is a street ambush in which Frost Nova can pin the party beside the Vengeful Phantoms before the tank has gathered the pull.
Abilities

Frost Nova
Inflicts Frost damage to nearby enemies, immobilizing them for up to 8 seconds.
Frost Nova damages and roots nearby players. Clear the landing area before crossing the arch and remove a root when it prevents a player from reaching safety.

Incorporeal Defense
Incorporeal Defense makes weapon attacks easier to dodge; spell damage remains useful while the tank gathers the ambush.
Tank- Cross the ambush arch only after the previous street pack is dead. Gather The Unforgiven and Vengeful Phantoms at the cleared side so a Frost Nova does not strand the healer among uncollected attackers.
Healer- Enter the arch with the group instead of being left behind when the ambush triggers. Keep healing through Frost Nova and the phantoms' Frost Shock slows while the tank gathers them.
Damage- Wait for the Vengeful Phantoms to reach the tank before using area damage. Avoid drawing a second street pack while rooted players are still recovering from Frost Nova.