The Cardinal Sins

Linneaus, Sin of Sloth:

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A floating island that can be found in the skies of the forgotten forest biome.

Bacchus, Sin of Gluttony:

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Can be found in a white hall in the plains biome.

Freya, Sin of Lust:

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Can be found in the taiga biomes in a castle.

Ebenezer, Sin of Greed:

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Can be found on a floating copper spire in the desert.

Odhran, Sin of Envy:

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Can be found in the oak forests in a giant tree stump.

Beowulf, Sin of Wrath:

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Can be found in a floating structure in the wasteland of wrath.

Leon, Sin of Pride:

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Can be found in the snowy plains/taiga/beach biome in a colosseum.

Lucifer, The Atrocity:

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Can be found in the forgotten forest in a floating eyeball.

Stone Warrior:

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Can be found in the plains biomes next to a cabin.

Drakara, Eternal Mourner:

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Can be found underground in a catacomb.

Cursed Knight:

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Can be found in the forgotten forest in a campsite.

Sinforged Armor:

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Robed Armor:

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In the forgotten forest biome, there are two types of floating pillars, normal ones with normal lanterns, and blue lit lantern ones. The blue ones contain a new block called Malevolichite Ore, upon mining this you will obtain Malevolichite Shards. This is useful to craft items such as weapons or to summon the first boss of the sins, the Sin of Sloth.

Defeating all the Sins in order goes as follows: Sloth > Gluttony > Lust > Greed > Envy > Wrath > Pride > Atrocity

How to spawn the Sin of Sloth (First Boss):

Right-Click the Malevolichite Shrine with a SoulWeaver Orb to summon the Sin of Sloth. Afterwards the next boss will need an orb that contains the essence of the previously killed boss.

Upon killing Drakara you may obtain her egg. Placing this down and waiting 5 minutes will hatch a baby Verdant Wyrm. After another 5 minutes it will mature into an adult and you will be able to tame it. Watch out as it might try attacking you once it'd grow up. After taming you can use them to travel the world by land.