Dream horses (tier 9) are not available through the usual breeding method, and take a lot of time and effort to achieve.
Tier 9 horses are end-game mounts in BDO and all have unique abilities. There are 3 types of dream horses.

Pegasus ( Arduanatt )
This tier 9 horse is a winged horse that uses its large wings to glide from high places safely.
They do not “fly”, but can jump off cliffs and safely glide downwards at high speeds.

Unicorn (Diné)

This tier 9 horse is a friendly mount that can buff targets to give them higher DP/Evasion and can also heal them.
The unicorn is a supportive mount that can prove useful in battle and is also the only horse unaffected by the Valencia Desert slow.

Doom
This tier 9 horse is the fastest dream horse thanks to its triple Instant Accel skill.
It also has more powerful attacks and stronger horse skills which scale with your AP.
They use fire and explosions to destroy their enemies in battle.

Obtaining a Courser Horse.

To begin awakening a Dream horse yourself, you will need a level 30 Tier 8 horse with the following skills:

• Charge
• Drift
• Sprint
• Instant Accel
• Sideways
• S: Instant Accel
• S: Sideways

This is also known as a Courser horse and it will have a gold horse symbol in the top right corner of it’s icon.

How to start Courser Training

Once you have a Tier 8 Couser at level 30, you can start “training” the horse. This involves feeding different materials into the horse until you have enough to do an “awakening attempt”.

To start, put the horse in the stable at Stonetail Horse Ranch or Grana (Melabee NPC – West Stable). Make sure it doesn’t have any gear equipped or items in the inventory. The option “Courser Training” will be available at the bottom.
Left Click Mouse Botton at your Courser Horse then Click " Courser Training "

Here you can train your horse in 3 different areas: Skill Training, Elegance Training and Strength Training. You must consume certain materials to train the horse in the different types of training. Each time you use 1 material, you increase it’s training exp by 1%. You can get a maximum of 180% exp in a training area, which give you a 90% chance of getting that particular horse.

To awaken the horse, you will need a total of 200% training across all training areas.
Eg. 100% Skill, 50% Elegance, 50% Strength.

Other ways to obtain T9 materials: