Villainous Difficulty Multipliers

Bug fix:
Cannon multiplier now respects doMobLoot gamerule.

Additions:
5 Difficulty Decreasing multipliers added!

Kinetic: Future technology embedded into your skin allows you to store up kinetic energy from attacks to release on your foes on your next attack, adding up to 50 hearts of damage maximum.
Undying: When you are about to die, you're instantly brought back to full health. Allows you to get back into the fight immediately, but does still increase your death counters.
Blacksmithing: Stronger understanding of proper anvil usage makes you less likely to damage it.
Fuel Efficient: Modern furnaces can get 4 times the use out of fuel.
Warranty: Tools may be replaced when they are destroyed.

As well as the keyword: keystothecity, which controls all difficulty decreasing multipliers.

Lastly, one more difficulty increasing multiplier:
Flammable: Entities on fire will stay on fire until water is applied (or they have died)