In Sith tradition, he took on his own apprentice, Ulic Qel-Droma(a fallen Jedi).

Together they recruited many apprentices, such was that many Jedi turned against their masters and killed them, succumbed by the Dark side's power.

Under his follow, his apprentices destroyed entire civilizations.

So, after a long period, a joint republic and Jedi taskforce traveled to Yavin to capture him.

Knowing his downfall would be soon, he summoned his energies and trapped his consciousness in his Masassi temples (his warriors were known as Massasi).

Years later, when Luke began to teach pupils, Exar returned in the body of Kyp Durron to rule once again. However, Luke's students united together and disspelled Exar's spirit.

 

Was originally a Jedi Knight, left his master, Vodo-Siosk Baas, because of his urge for more power.

Traveled to Onderon, and met Freedon Nadd (an Ancient sith Lord), who furthered his Training.

Exar traveled to the Sith Mausoleum planet of Korriban.

There, the spirits of ancient sith lords tested his resolve.

He was crushed in a cave-in of many rocks, and could not call upon the force to help himself.

By giving in to his fear and Rage, he was able to heal himself and clear the obstacles.

When he left those caverns he was a new man, fueled with the powers of the Dark side.

Kyp Durron (below)