This is a SpookyJam 2021 entry.
https://spookyjam.mcmoddev.com/
Death Generators harness the power of magical pumpkins to create FE for you. Entities in range of the generator take damage over time and damage dealt is proportionate to the energy produced.
there are 3 tiers of generators:
1. Pumpkin of Pain
2. Pumpkin of Suffering
3. Pumpkin of Hellfire
Each one deals more damage per tick and produces exponentially more energy. All settings are configurable including effected entities, which are managed by an entity type tag.
There are also upgrade items you can craft to upgrade in-place generators (crouch right-click to upgrade).