Dwarf King
Sacrifice Items: Goblin King's Skull + Goblin Doll
Mapset: Mansion
Number Of Rounds: One
NPCs: Goblin, Goblin Mage, Goblin Commander, Goblin Shaman
Number Of NPCs: 78
Quest Boss Drops: Goblin King's Skull, PG 65, Goblin King's Axe, Crimson Necklace.
Lich
Sacrifice Items: Devil's Dictionary + Enormously Huge Skull
Mapset: Dungeon
Number Of Rounds: Four
NPCs: Unholy, Giant Skeleton, Skeleton Commander, Skeleton, Mage.
Number Of NPCs: 78
Quest Boss Drops: Pg 65, Devil's Dictionary, Enormously Huge Skull, Lich's Tail, Wings of Catastrophe.
Anemeron
Sacrifice Items: Mysterious Skull + Skeleton Doll
Mapset: Prison
Number Of Rounds: Four
NPCs: Unholy, Giant Skeleton, Skeleton Commander, Skeleton, Mage.
Number Of NPCs: 78
Quest Boss Drops: Pg 65, Devil's Dictionary, Enormously Huge Skull, Anemeron's Sword, A shoe, Odd Gun x 2.
Superion
Sacrifice Items: Large Skull + Skeleton Doll
Mapset: Prison
Number Of Rounds: Four
NPCs: Unholy, Giant Skeleton, Skeleton Commander, Skeleton, Mage.
Number Of NPCs: 78
Quest Boss Drops: PG 65, Enormously Huge Skull, Superion's Sword.
Giant Lizard King
Sacrifice Items: Platinum Ring + Gold Ring
Mapset: Prison
Number Of Rounds: Three
NPCs: Mini Golem, Mini Kobold King, Kobold, Kobold Commander, Kobold Shaman.
Number Of NPCs: 26
Quest Boss Drops: Cursed Pampow Idol, Pampow Idol, Broken Gear, High-Class Gear.
Broken Golem
Sacrifice Items: High-Class Gear + Kobold Doll
Mapset: Prison
Number Of Rounds: Three
NPCs: Mini Golem, Mini Kobold King, Kobold, Kobold Commander, Kobold Shaman.
Number Of NPCs: 52
Quest Boss Drops: Cursed Pampow Idol, Pampow Idol, Broken Gear, Cursed Cross, Blessed Cross.
Goblin King
Sacrifice Items: Goblin's Skull + Crimson Necklace
Mapset: Mansion
Number Of Rounds: One
NPCs: Goblin, Goblin Mage, Goblin Commander, Goblin Shaman.
Number Of NPCs: 78
Quest Boss Drops: Goblin King's Skull, PG 65, Goblin King's Axe, Crimson Necklace.
Ghost King
Sacrifice Items: Cursed Cross + Blessed Cross
Mapset: Mansion
Number Of Rounds: Four
NPCs: Unholy, Giant Skeleton, Skeleton Commander, Skeleton, Pampow, Fallen Warrior Elite
Number Of NPCs: 100
Quest Boss Drops: N/A
That's all the basic bosses you need to know to level up =)
All credits go to Techno.