Baium is an epic boss that resides on the top floor of Losttower.
You can access it with at least 3 Grand Resets.
There's a portal in Losttower 7 at coordinates 214 39.

Baium respawns 11-13 hours after a server restart or 120-144 hours after death.
On the top floor of Losttower, you'll find Baium imprisoned in stone by angels.

Hitting the statue will cause angels to appear, who will use all their might to prevent you from waking Baium.
The angels will debuff you and remove buffs, and will reappear after 1 minute of death.
If no one touches the statue for 10 minutes, the angels will leave.

Waking Baium will cause the angels to disappear.
Baium heals, inflicts debuffs, and deals lethal blows.

If Baium is not touched within 10 minutes, the angels will imprison him in stone.