Andas is the final Tremodeboss fought in the Underworld biome and is also the last boss in the entire Tremor Mod. Its fight is long and difficult and requires large amounts of preparation. Andas' phase 2 form is True Andas and will only spawn in during the day, if summoned during the night it won't start the second phase, stopping the fight from being completed and wasting the summon item due to Andas' first phase not dropping anything.
Andas floats rapidly around the player, phasing through blocks and will also randomly teleport around the player. Once defeated, he will transform into True Andas and will deal more damage and have higher health.
Andas flies around, firing small yet slow-moving flaming orbs that phase blocks and will also occasionally fire large flame spheres in a circular pattern that fly off in random directions.
True Andas acts in much the same way as Andas does, but summons Infernal Skull projectiles, Molten Spirits, and Undead Wyrms.
Andas and True Andas' speed increases, and it gains the ability to shoot small pieces of fire.
Keep in mind that Andas itself has no drops, so in reality, this fight is one single boss with a combined 235,000 (or 470,000 in Expert Mode) health.
Andas can be summoned only during the daytime. He will not despawn when it turns to night, however, True Andas will not spawn even if Andas is defeated.