The Cardinal Sins

Linneaus, Sin of Sloth:

Bacchus, Sin of Gluttony:

Freya, Sin of Lust:

Ebenezer, Sin of Greed:

Odhran, Sin of Envy:

Beowulf, Sin of Wrath:

Leon, Sin of Pride:

Lucifer, The Atrocity:

Stone Warrior:

Drakara, Eternal Mourner:

Cursed Knight:

Sinforged Armor:

Robed Armor:

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.