Here "terror" represents the things that will cause them to be terrified. AT: "I will send disasters that will terrify you" (See: [[rc://en/ta/man/translate/figs-metaphor]])
"will slowly take away your life" or "will slowly make you die." It is the diseases and the fever that will do this.
# You will plant your seeds for nothing
The phrase "for nothing" means that they would get nothing from their work. AT: "You will plant your seeds in vain" or "You will plant your seeds, but you will not get anything from them" (See: [[rc://en/ta/man/translate/figs-idiom]])