When we attack the Maw with the Shadowlands pacts in WoW Patch 9.1, we'll be doing so not only to put a stop to the dungeon master, but also to pick up cool rewards. Some of those rewards have now surfaced on the test server for the upcoming update, Chains of Domination. Wowhead's dataminers have so far discovered two special mounts that players can unlock via the Maw Attacks.

Hyenas and Gorms for the Maw Strikers

So far, the current build of patch 9.1 on the test server includes two mounts, one for the Necrolords attacks and one for the Night Fae attacks. The Undying Darkhound is included with a low probability in the War Chest of the Undying Army. You will get this when you complete the Necrolords' attacks at the Damnation Stronghold. This mount uses the same model as the Battlebound War Hound or the War Mending Gloom Hound. The color in this case is a yellowish green.
WoW: Patch 9.1 - The Pacts Reward You for Maw Attacks with Cool Mounts (2) Source: Wowhead Those who support the Night Fae in their attacks on the Maw at the Crucible of the Damned will receive the War Chest of the Wild Hunt, which may include the Gorm mount Legsplitter if you're lucky. This mount uses the same model as the Finsterbau Hardplate or the Pale Acid Maw, and has a bluish-turquoise hue.
WoW: Patch 9.1 - Pacts reward you for maw attacks with cool mounts (1) Source: Wowhead Which mounts you can get from the Venthyr and Kyrians, we currently do not know. However, we assume that the developers will take a similar approach here and use color variants of already existing mounts as rewards. As soon as we learn more about this, we will inform you promptly.