Neverwinter

There are 6 minor Heroic Encounters and 1 Major Heroic Encounter in Barovia. The minor encounters pop up around the map and last for a set period of time, and are as follows:

Restless Dead -- (2458, 763)
Merchant Misery -- (1561, 1904)
Martikov Merchants -- (2028, 800)
The Howling -- (650, 627)
The Taken -- (1660, 208)
Hostage! -- (185, 976)

There is 1 Major Heroic Encounter similar to the Tyrant and the King of Spines in Chult, which is Yester Hills. You'll see this often called out in zone chat, and is also directly related to the heroic requirement for the weekly quest. Complete all 7 of these encounters, and the achievement should unlock. You can see how many you've done in Journal --> Achievements --> Heroic Encounters --> Barovian Hero

Edit: Fuzzmeister J -- You do not get credit in a group. I did all of them in a group with no progress and the moment I went solo, they counted.