Gae Assail allowed Izaya to manipulate electromagnetic waves. He used his sigil to run the Darwin's Game app, making it unnecessary to have an internet connection to use it. It was later revealed that he can cremate bodies if he converged the electromagnetic waves he was controlling. Using his sigil, Izaya could also create barriers that could block sigils like Beelzebub, flatten it to use as a blade to cut opponents, or fire it as a laser.
- Gae Assail is the Celtic name of the spear of Lugh from Celtic mythology. It is said to be impossible to overcome which is possibly a reference to how Izaya is considered to be the strongest sigil user.