Torva-mes does not spawn on its own and requires a Cursed Rune in order to be summoned.
Torva-mes always aims straight for the player(s) and proceeds to dash into them at a fast pace whenever they get too close. Throughout the fight, it will summon Wraith Scythes in to battle at certain portions of HP. The Wraith Scythes attempt to dash into the player(s) while they're alive, and must be killed before Torva-mes can take more damage.
Below half it's max HP, Torva-mes will summon a fast, rebounding projectile, known as Slaughter EX, that will explode into a spray of 8 vibrant red bullets upon hitting 5 surfaces. A message will be broadcast in the chat before this happens, so players have a small time period to prepare for and dodge the incoming attack.
If the player leaves the Underworld while Torva-mes is alive, Torva-mes will become nearly invulnerable to all damage. The Scythes however, remain unaffected.