Immortality was a blessing for the strong and a curse for the weak, an indefinite amount of time could be well spent in the hands of the wise or a self Torment in the hands of the foolish, what is 50, 100 or 1000 years to a being like Ominous, i will tell you that it was nothing but a blink of an eye, yet as he was a human mortal in his past life he knew of its Importance as not to waste it.
40 years was spent in his reform of the Underworld, new powerful beings have been added to his realm, his new shades would serve him well, Vulgath as the First shade of Ominous and the most Important of them was being guided by Ominous as to not Ascend into godhood until he felt his potential was saturated, but for the Other shades they were created to be God aspects of the different Dark undead races of the Oblivion realm and rule over them.