Ublaz was a former pirate captain and the ruler of a tropical island called Sampetra, a port for corsair vermin to set anchor at. Ublaz ruled ruthlessly from his palace, forcing the pirate captains to pay tribute to him in order to stay at the island. To enforce his laws were savage Monitor lizards (lead by Lask Frildur) that acted as his shock troops, as well as a military of trident-bearing rats.
Emperor Ublaz was tall, handsome, and polite, as well as very cunning. His most known attribute was his uncanny ability to hypnotize others by staring into their eyes, hence his nickname "Mad Eyes". He used this power to tame the cannibalistic Monitors and make them serve him. He could also 'kill' someone with his stare, gazing at them so intensely that they lost their mind and committed suicide. In order to both practice his hypnotizing and show his full power, he would go into a cult-like staring match with a deadly coral snake that he kept in a secret room. Ublaz always won, and forced the snake into silent submission.
Ublaz coveted only one thing: a set of six pink pearls owned by the otter Lutra and his clan. The Emperor sent out corsair ships to retrieve these for him, and the vermin pirates slaughtered the otter tribe and stole the pearls. Over a set of circumstances, the pearls were lost, and Ublaz continued his search for them. Meanwhile, several corsair captains had started an uprising against the Emperor, and they rallied in battle against him. Ublaz spent most of his time trying to keep control over the rebels and outwitting their crafty leader, the fox Rasconza.
When the warriors of Redwall came to the island to rescue their captured Abbot, their leader, Martin, dueled with Ublaz down in his snake chamber. During the fierce battle, Martin forced Ublaz backward, and he stepped on the tail of the sleeping coral snake. It struck and bit his leg, paralyzing and eventually killing him. He never obtained the pearls.