Ertai

"Don’t worry, Gerrard,” said Ertai. “I’m sure the crew will come to your rescue as quickly as they came to mine."

Ertai is a blue aligned human wizard turned blue and black aligned Phyrexian wizard from Magic: the Gathering. He is a brilliant but arrogant mage who learned from the head wizard of the Tolarian Academy Barrin and signed up to join the Weatherlight Crew.

Journey to Rath
The Evincar of Rath Volrath managed to capture the captain of the Weatherlight Sisay and in order to find her, they need a mage to manipulate the powerstone that allows the ship to travel between planes to find Rath. The ship's engineer Hanna suggested bringing her father Barrin. Barrin declined and instead offered to send Ertai with them. He was one of Barrin's top students and had been certified for explorations. Hanna was skeptical of his qualifications and challenged the mage resulting in Ertai winning. Once the crew arrived on Rath, they were ambushed by the Phyrexian flagship Predator helmed by Greven il-Vec and the engine was badly damaged. While the rest of the crew went into Volrath's stronghold to find Sisay, Ertai stood behind to open Planar Portal in case things went wrong. While trying to open it, a Soltari named Lyna offered to help in exchange for the rest of his people to use it as well. The two were successful but with the Weatherlight being tailed by the Predator, the ship went through the portal while leaving Ertai behind.

Nemesis
After he was abandoned, he was captured by Greven and taken to Volrath's stronghold. He spent much of his time incarcerated but managed to gain the affection of a Phyrexianized elf named Belbe. It was because of her that he was able to control flowstone. Because of their relationship Ertai was a contender to become the new Evincar after Volrath left. But one of the other contenders and former allies Crovax was too strong and aggressive to challenge so he spent his time trying to escape. He witnessed the battle between Volrath and Crovax and secretly helped Crovax win. He later found out that Belbe was killed by the elf Eladamri and he used Belbe's portal to escape. With all of the portal's energy gone and with all hope lost, Ertai submitted to Crovax, became a phyrexian, and became his servent.

Invasion
After the trauma of his abandonment by the Weatherlight Crew and the death of his love Belbe, Ertai resented his former friends and wished to destroy them. After the Rathi Overlay brought the Phyrexians to Dominaria, Ertai joined Crovax on the predator and caught Gerrard Capashen and the goblin Squee(on accident). They were transported to the Stronghold and Ertai gave Squee resurrection powers. This was done so he and Crovax could endlessly kill him as many times as they want. Ertai delighted in slaughtering Squee multiple times, but when Squee accidentally overloaded the Phyrexian healing machine, it exploded and killed Ertai in the process.