|Alias(es)||The Emperor, De Leider|
|Race||Dreamscape Demon (Former Mage)|
|Main Ability||Dreamscape Demon|
|Birthplace||New Amsterdam, New Netherland|
|Affiliation(s)||The New Amsterdam Penose|
|Base of Operations||Haarlem, New Amsterdam|
- "Mister Sandman, at your service."
- ― Mathias taunting Ozias Orson before trapping him in the Dreamscape
Mathias van Delden is the leader of the New Amsterdam Penose, and one of few members with magical abilities. Originally a Mage, Mathias managed to trap himself into the Oneiric Realm, where he met the Dreamscape demon Orisul. Making a deal to escape the Oneiric Realm, Mathias himself gained the abilities of a Dreamscape demon when he took the burden from Orisul. Using these abilities to take over the Penose, Mathias took on the shade name of Klaas Vaak, referring to the Dutch name of the Sandman.
- Dreamscape Demon - In exchange for leaving the Dreamscape, Orisul converted his burden as a dream demon to Mathias, granting him many abilities.
- Dreamscape Manipulation - Mathias' being a demon of the Dreamscape, has full control over the Oneiric Realm, making him a formidible opponent when his opponents fall asleep.
- Nightmare Control - Due to being able to control the Dreamscape, Mathias can control nightmares as well as regular dreams.
- Oneiric Constructs - Any items Mathias' has created in the Oneiric Realm he can transfer to reality.
- Dream Imprisonment - Once a victim enters the Dreamscape, Mathias is capable of trapping them there, though doing this takes lots of concentration.
- Telekinesis - One non-dream ability Mathias was gifted was the ability to use telekinesis against opponents.
- Pain Inducement - Mathias likes to use his telekinesis on the nerves of others, causing intense phantom pains.
- Dead Heart - Due to the shock of being converted into a Dreamscape Demon and as part of the process, Mathias' heart no longer functions. He also no longer has blood.