Hogwarts Legacy Foal Of The Dead is the second side quest as part of Deek’s questline, allowing you to upgrade your Room of Requirement even more. In Foal Of The Dead Quest, Deek will teach you how to use the breeding pen for breeding the Thestrals.
But before you start breeding the Thestrals, you’ll have to rescue a male and a female, then conjure a breeding pen in the new biome available. The main requirements to start Foal Of The Dead Side Quest are to complete The Plight Of The House-Elf Side Quest, Deek’s first side quest, and advance the story until you’ve finished Charles Rockwood’s Trial Main Quest.
Then, Professor Weasley will send you a message through the Owl Post letting you know that Deek wants to speak with you about breeding the rescued beasts. You can find Deek in the same place as always, in your Room of Requirement.
Talk to him to begin the Foal Of The Dead Side Quest. If you want to learn how to build a breeding pen, he will ask you to bring a pair of Thestrals to the room, one male and one female, and purchase a breeding pen spellcraft. Let’s see where we can rescue the pair of Thestrals first.
How to Rescue a Male and a Female Thestral
After you finish the conversation with Deek, he will mark a den inhabited by Thestrals in the northeastern part of the World Map, in the North Ford Bog Region.
You will find several Thestrals, but you’ll have to rescue only one male and one female. There is a high chance you might already have a Thestral, so check your quest log to see which one you have to rescue left.
To tell the gender of a Thestral, aim toward it and check the top of the screen near the name for the symbol. If it has this ♂ symbol, it’s a male, and if it has this ♀ symbol, it’s a female.
Equip the Nab-Sack Utility spell learned during The Elf, The Nab-Sack, and the Loom Main Quest and cast it on the Thestral to rescue and hold it. Now that we have a pair of Thestrals, let’s see where to purchase a breeding pen spellcraft.
Where to Purchase a Breeding Pen Spellcraft
To purchase a breeding pen spellcraft, head to Hogsmeade and visit Thomas Brown at the Tomes and Scrolls Shop. You’ll have to pay 1000 Galleons to purchase the spellcraft.
If you don’t have enough money, you can sell your unwanted gear or capture more beasts and sell them to Brood & Peck in Hogsmeade for 120 Galleons each. After you’ve obtained everything, let’s return to Deek in the Room of Requirement and learn how to use the breeding pen.
How To Conjure a Breeding Pen
While you speak with Deek, another vivarium will appear in your Room of Requirement, with a biome fitting for the Thestrals. Enter the vivarium, press (R1)/(RB) to manage the beasts, select the Thestrals, and press (X)/(A) to add them to the vivarium.
Now, equip and cast the Conjuring Spell, select the Beast Items, and choose the Breeding Pen. Find a fitting place in your vivarium and press (X)/(A) to conjure.
How To Use the Breeding Pen To Breed Thestrals
Once you’ve conjured the breeding pen, interact with the pedestal in the front and choose Thestral. The breeding process takes 30 minutes in real time, so you’ll have to wait, or you can do other quests in the meantime.
How to Groom and Feed the Thestral Offspring
After the 30 minutes, when the Thestral Offspring is born, equip and cast the Beast Petting Brush Spell and Beast Feed on it. You can also interact with it to receive 3 Thestral Hair for upgrading your gear.
Return to Deek and give him the news about the newborn Thestral. He will tell you a story about a phoenix, which hints at his next quest.