Ghoul is one of only three races that can be obtained through a quest.
Ghoul gives various stat boosts, most notably buffing the user's speed during the night, and allowing the player to leech other players' health, making it good for survivability and overall combat effectiveness. It is a great choice for PvP due to its ability to reduce cooldowns quickly and be more mobile while having amazing life leech when awakened to V4. This race is strong in almost every aspect, except for its relatively weak armor support, which is compensated by its life leech abilities. Ghoul does not require anything to switch to after already obtaining it from the Experimic, similar to Draco.
V2 Completing the Alchemist's quest. To take this quest, the player has to have completed the Colosseum quest.
V3 Completing Arowe's quest, which varies depending on the race. Ghoul's V3 quest is:
Killing 5 players. (They can be the same player, as the quest suggests to kill 5 players not to kill 5 different players, the player does not need to take others' bounties as there's no levels requirement.)
The quest resets every time rejoining the game.
V4 Completing the Temple of Time puzzle, then doing the Trial of Carnage.
Full steps can be found on the Race Awakening page.