• Hero Pets Not Allowed : No pets can be summoned while this is active.
  
• Hero Potion Cooldown Increased : Increased potion cooldown by 5/10/10 seconds
  
• Hero Attack Speed Decreased : Reduced attack speed by -30/-45/-60%
  
• Hero Energy Blocked : Reserved 400/700/1000 Energy
  
• Hero Magical Resistances Decreased : Elemental and Vitality resistances reduced by -50%
  
• Hero Non-Magical Resistances Decreased : Physical, Pierce, Poison and Bleeding resistances reduced by -50%
  
• Hero Spell Cast Speed Decreased : Reduced casting speed by -30/-45/-60%
  
• Hero Defensive Ability Decreased : Reduced defensive Ability by -30%
  
• Hero Move Speed Decreased : Reduced running speed by -30/-45/-60%
  
• Hero Offensive Ability Decreased : Reduced offensive Ability by -30%
  
• Hero Leech Resistances Decreased : Life Leech and Energy Leech resistances reduced by -75%
  
• Hero Status Resistances Decreased : Stun, Trap, Sleep, Disruption, Petrify, Freeze and Slow resistances reduced by -75%

• Enemies Spawn Trap on Death : Enemies spawn a single runic mine where they have been defeated
  
• Enemy Size Increased : Enemies are twice as big, have -20% Total Speed but permanent 33% Damage Absorption
  
• Enemy Awareness Increased : Enemies can see from further, making them more aggressive
  
• Enemy Size Decreased : Enemies' size is halved, have +15% Total Speed and +10% Movement Speed, but also -25% Physical, Pierce, Bleeding, Poison, Vitality and Elemental Resistance
  
• Enemies Inflict Fumble : Enemy attacks cause 50% Chance to Fumble Attacks for 3 seconds
  
• Enemies Have Sharp Ice Weapons : Enemy attacks have 60 Bleeding damage over 3 seconds + 50 cold damage bonus
  
• Enemies Have Venomous Weapons : Enemy attacks have 60 Poison damage over 3 seconds + 25 vitality damage + 5% Reduction to Health bonus
  
• Enemies Drain Energy : Enemy attacks have 60 Energy Leech over 3 seconds
  
• Enemies Drain Health : Enemy attacks have 60 Life Leech over 3 seconds
  
• Enemies Drain Health & Energy : Enemy attacks have 60 Life Leech AND Energy Leech over 3 seconds
  
• Enemy Projectiles Explode : Enemy projectiles have 50% Increase in Projectile speed, and they deal damage over 2 meter radius
  
• Enemy Attack Speed Increased : Enemies have +30% Attack Speed
  
• Enemy Dexterity Increased : Enemies have +30% Dexterity
  
• Enemy Intelligence Increased : Enemies have +30% Intelligence
  
• Enemy Base Stats Increased : Enemies have +15% Strength, Intelligence and Dexterity
  
• Enemy Strength Increased : Enemies have +30% Strength
  
• Enemy Magical Resistance Increased : Enemies have 75% Fire, Lightning, Cold and Vitality Damage Resistance
  
• Enemy Non-Magical Resistance Increased : Enemies have 75% Physical, Pierce, Bleeding and Poison Resistance
  
• Enemies Retaliate With Burning Blood : Enemies have 75 Burn, Electrical Burn and Bleeding retaliation over 3 seconds
  
• Enemies Retaliate With Chilling Poison : Enemies have 75 Frostburn, Poison and Vitality Decay over 3 seconds
  
• Enemies Reflect Damage : Enemies reflect 20% damage
  
• Enemy Cast Speed Increased : Enemies have +30% Casting Speed
  
• Enemy Defensive Ability Increased : Enemies have +30% Defensive ability
  
• Enemy Move Speed Increased : Enemies have +30% Movement Speed
  
• Enemy Offensive Ability Increased : Enemies have +30% Offensive ability
  
• Enemy Energy Regeneration Increased : Enemies regenerate +50/75/100 health per second
  
• Enemy Health Regeneration Increased : Enemies regenerate +50/75/100 energy per second
  
• Enemies Spawn Insects on Death : Enemies spawn bees on death. They inflict bleeding and poison damage
  
• Enemies Spawn Ghosts on Death : Enemies spawn a ghost on death. They have a long-ranged Mana Drain attack

Digging into the text files of the game, I found a handful of text entries that hinted that the developpers had lots of ideas for Tartarus' modifiers, but many of them have been scrapped. For curiositiy's sake, here's what I could salvage :

• Hero Skill Cost Doubled
  
• Hero Camera Locked
  
• Hero Emits Aura Debuffing Other Heroes
  
• Hero Health Constantly Draining
  
• Hero Energy Constantly Draining
  
• Hero View Obscured
  
• Hero Unable to Block or Dodge
  
• Hero Resistances are Depleted
  
• Hero Speed Boost Not Allowed
  
• Hero Health Does Not Regenerate
  
• Hero Energy Does Not Regenerate
  
• Hero Unable to Use Potions
  
• Hero Unable to Use Skills
  
• Hero Gets No Bonuses From Helms
  
• Hero Gets No Bonuses From Rings
  
• Heros Get No Bonuses From Bracers
  
• Hero is Turned Into a Monster
  
• Player Constantly Losing Life
  
• Player Constantly Losing Energy
  
• Player Skills Disabled
  
• Player Skills Cost Doubled
  
• Player Skills Slow Recharge
  
• Player gets No Bonus from Torso Armor
  
• Player gets No Bonus from Arm Armor
  
• Player gets No Bonus from Leg Armor
  
• Player gets No Bonus from Amulets

• Enemies Explode on Death
  
• Enemies Spawn Toxic Clouds on Death
  
• Enemies May Retaliate with Slow
  
• Enemies May Retaliate with Root
  
• Enemies May Retaliate with Energy Burn
  
• Enemies May Retaliate with Stun
  
• Enemies May Retaliate with Freeze
  
• Enemies May Retaliate with Sleep
  
• Enemies May Retaliate with Petrification
  
• Some Enemies Inflict Contagious Burn
  
• Enemies May Avoid Magical Damage
  
• Enemies May Avoid Non-Magical Damage
  
• Enemies Call For Help
  
• Enemies cause Slow
  
• Enemies cause Trap
  
• Enemies inflict Bleeding damage
  
• Enemies inflict Cold damage
  
• Enemies inflict Fire damage
  
• Enemies inflict Lightning damage
  
• Enemies inflict Physical damage
  
• Enemies inflict Pierce damage
  
• Enemies inflict Poison damage
  
• Enemies inflict Vitality damage
  
• Enemies inflict Energy Burn
  
• Enemies inflict Stun
  
• Enemies inflict Freeze
  
• Enemies inflict Sleep
  
• Enemies inflict Petrification
  
• Enemies spawn a creature on death
  
• Enemies' primary resistances increased to 100% chance

There was also reworded versions of both existing and trashed modifiers, I didn't included those.