In Config.lua, you'll find all the EnemyData that you want to be added DropRate.

Code example explainedOlympusEnemyData.BaseVulnerableEnemy.DropRate = {
  DropChance = 0.1,
  DropReward = {
WeaponUpgradeDrop = 0.01,
MetaDropRange = 0.29,
GemDrop = 0.25,
StackUpgradeDrop = 0.10,
LockKeyDrop = 0.15,
GiftDrop = 0.15,
--StackUpgradeDropRare = 0.02,
--HermesUpgradeDrop = 0.02,
  }
}

• OlympusEnemyData: static information about the Library you want to edit.
• BaseVulnerableEnemy: enemy name or enemy type you want to edit.
• DropRate: static variable to add drop rate to specified enemy.
• DropChance: chance to drop something from the DropReward list. Value between 1.0 and 0.01.
• DropReward: list of possible reward if the DropChance was successful. Only 1 Reward will be drop. Starting from the top of the list, each reward will have a chance to be selected, using the value next to the reward. Value between 1.0 and 0.01. Total value of all reward should equal 1.0. See below DropRewards to see the list of possible Rewards you can add.
  

• BaseVulnerableEnemy: All basic enemies without power ups
• BaseBossEnemy: All boss
• Elite: Enemies with extra health with power ups
• SuperElite: Most Mini-boss
• 
  
  

• HeavyMelee: Wretched Thug
• ... See EnemyData.lua
  

• HealDropRange: Food healing, consumed on touch.
• MetaDropRange: Darkness, consumed on touch.
• GemDropRange: Gems, consumed on touch.
• HealDropMinor: Food healing, interaction.
• GiftDrop: Nectar, interaction.
• SuperGiftDrop: Ambrosia, interaction.
• LockKeyDrop: Chthonic Key, interaction.
• MoneyDrop: 100 Obols, interaction.
• RoomRewardConsolationPrize: Onion, interaction as if it was a room reward.
• RoomRewardHealDrop: Food healing, interaction as if it was a room reward.
• RoomRewardMaxHealthDrop: Centaur Heart, interaction as if it was a room reward.
• RoomRewardMoneyDrop: 100 Obols, interaction as if it was a room reward.
• RoomRewardMetaPointDrop: Darkness, interaction as if it was a room reward.
• EmptyMaxHealthDrop: Empty Centaur Heart, interaction.
• ChaosWeaponUpgrade: Chaos Boon, interaction.
• GemDrop: Gems, interaction.
• GemDropRunProgress: Gems that can give money when you have the perk, interaction.
• SuperGemDrop: Diamond, interaction.
• SuperLockKeyDrop: Titan Blood, interaction.
• StackUpgradeDrop: Pom of Power, interaction.
• StackUpgradeDropRare: Double Pom of Power, interaction.
• WeaponUpgradeDrop: Daedalus Hammer, interaction.
• HermesUpgradeDrop: Hermes Boon, interaction.
• ... See ConsumableData.lua
  

• StackUpgradeDrop: