Answer:
Vikings use this for warmth.
I have one door and five rooms what am i
As destructive as life, As healing as death; An institutioner of strife, Just as prone to bless. It is all that is good, Yet with an evil trend; As it was the beginning of things, It can also be the end.
You use a knife to slice my head. And weep beside me when I am dead.
Long and slinky like a trout, never sings till it's guts come out.
They are many and one, they wave and they drum, Used to cover a state, they go with you everywhere.