napalm

turtle.select(1)
local sensor = peripheral.wrap("right")
local mobLimit = 100
local delay = 20
local burnTime = 20

while true do
  if #sensor.getMobIds() > mobLimit then
    -- i love the smell of napalm in the morning
    turtle.placeUp()
    sleep(burnTime)
    while #sensor.getMobIds() > mobLimit do
      sleep(math.floor(burnTime / 2) + 0.1)
    end
    turtle.placeUp()
  end
  sleep(delay)
end