Shadow.

Since these riddles went mostly unanswered (and forgotten), I shall reveal the answers.

His beauty shines bright,
and then it darkens.
A line divides him,
but shows history.

VIVEC

Smart you must be,
to kill with me.
Thoughtful you must be,
to wield my power.

SHEHAIi

The tiles of the floor make a picture of a bear.
An Imperial hidden among letters and words. Follow closely.
First the fourth and fifth, then the thirty-fourth, then the thirty-fifth, followed by the thirty-seventh.

TIBER SEPTIM

Inside of us it lives.
A wepon, even a sealent for the re-living.
It can help or hurt your beautiful life.
The masters can find infanite life.

MAGICK

Dancing over the melting base,
I hurt those who would dare dance with me.

FIRE

You lose, I gain.
You drop, I bring you up.
You die, you live.
I am the cause of these and more,
What am I?

NECROMANCER

Drat... too easy.