Basta seguir o modelo da tabela; adicionar o nome do monstro, junto da posição onde quer que ele de spawn:

 

local config = {
    monster = {
        [1] = {name = "Witch", position = {x = 79, y = 88, z = 6}},
        [2] = {name = "Hydra", position = {x = 79, y = 89, z = 6}},
        [3] = {name = "Dragon", position = {x = 79, y = 90, z = 6}},
    },
    removeTime = 20 -- Configurado em minutos
}

function onThink(interval, lastExecution)
    for index, monster in ipairs(config.monster) do
        local creature = doCreateMonster(monster.name, monster.position)

        addEvent(function()
            if not isCreature(creature) then
                return
            end
            doRemoveCreature(creature)
        end,  config.removeTime * 60 * 1000)
    end
    return true
end

 

local monstersTable = {
	[1] = {name = "Witch", position = {x = 79, y = 88, z = 6}, removeTime = 20},
	[2] = {name = "Hydra", position = {x = 79, y = 89, z = 6}, removeTime = 20},
	[3] = {name = "Dragon", position = {x = 79, y = 90, z = 6}, removeTime = 20},
}

function onThink(interval, lastExecution)
	for index, monster in ipairs(monstersTable) do
		local createMonster = doCreateMonster(monster.name, monster.position)
		if createMonster then
			addEvent(function()
				local creature = getCreatureByName(monster.name)
				if creature and isCreature(creature) then
					doRemoveCreature(creature)
				end
			end, monster.removeTime * 60 * 1000)
		end
	end

	return true
end