This datapack add some difficulty to survive in your world.

You have 4 scoreboards:

  One for summon a resistant zombie (score = 4 000)

  the second for summon a fast creeper (score = 8 000)
  the third for summon a basic witch (score = 16 000)
  and the last for summon an elder guardian (score = 64 000)
An higher score mean a more rare summon