Summery first version

I have failed once. I shall not fail again
My mission is to kill and eradicate all human resistance off
the planet.
I have been trained a few million years ago bay the dark
lord to kill and slaughter humans.
I have been given powers beyond my wildest desires, moving
faster then a dart, the strength I was given gave me the
ability to move mountains.
It took me over five hundred years to dwindle the number of
humans from almost a million down to seven, hoping they
would die off. I have been given even more powers, my
physical strength was legendary I cased craters bay jumping
one hit of mine could shatter the crust of the planet,
farther more I could move thru time and space destroying
star systems as I walked. Until one day I crossed upon a
planet with creators with powers dwarfing my own, and they
didn't like outsiders, they striped me from my powers and
killed me as I killed so many humans.
Now I have been sent back bay the dark powers to this time,
striped from my powers as a punishment for failing in
protection of the dark lord.
My quest isn't over, now that humans infest the planet.
The time has come the end their reign and send them back to
oblivion, as written I the ancient texts, oblivion awaits.
Humans beware, I am Halar of the dark forces. Your souls are
mine.

Summery second version

Dark times came upon the earth, the era of demons, the
demons enjoy their eternal lives, torturing all to feed
their sadistic hunger, until they stumbled upon a creature
that could destroy them all. Their strength wasn't physical
, but their souls and minds were pure and could blonde with
purity even the darkest demonic powers. their rate of
reproduction was incredibly fast they duplicated their
amount every year, and commenced powerful attacks on the
demonic empire, their mental powers were unstoppable, until
they got to the lair of the dark lord, but he was ready for
them, he has prepared for this battle for many years.
Casting spells to block their pureness of the creators, he
captured one of them used him, and corrupted is pure soul,
making it wretched, dark and evil, he named him Halar-soul
taker. He gave him the powers of a demon witch triggered
very powerful affects to his body, ultimate speed, strength
that was never seen before on this earth, un like a demon
the purity of the creatures had no effect on him. in the
attack on the dark lords lair many creatures lost their
lives, all killed by his hands. Every one he killed made his
powers grow by consuming their souls. After that attack the
dark lord commanded him to kill every one of thaws creatures
he called halmans - pure souled.