During the Time of Troubles, the then-demigod Xvim was imprisoned within the depths of Zhentil Keep. After the end of the Time of Troubles and his father's demise, Iyachtu Xvim was granted his father's command of hatred, strife, and tyranny, and elevated to godhood. For little over a decade, Xvim reigned as a minor god, a feeble successor to his fearsome sire. During his existence, Xvim was petty, power-hungry, and ruthless, in some ways like his father. However, he was not nearly as strong, especially in comparison with the other "new" deity in the Faerunian pantheon, Cyric.
His most elaborate scheme during this period was when he impersonated the Krynnish god Sirrion, nearly tricking Lathander into transferring the divine energy of Tymora and Beshaba]] into him. Lathander was convinced that he was actually merging Tymora and Beshaba into a single deity, Tyche. Fortunately, the scheme was thwarted.
Iyachtu Xvim's Realm, the Bastion of Hate, was in Chamada, the second Layer of Gehenna. It was a fortress surrounded by rivers of lava.
On Midwinter night of 1372, the young god was consumed by a blazing green fire, from which emerged a resurrected Bane. Nearly all former priests of Xvim (who in turn shifted to his allegiance after the death of his father) repledged themselves to the Church of Bane. Xvim is now considered a dead god, and for as long as his father holds on to divinity, he will probably remain as such.
Source: Faiths & Avatars, Tymora's Luck, On Hallowed Ground, Forgotten Realms Campaign Setting (3rd edition)