Hearthpwn

nop

Inb4 parzival's answer was the closest you will get in knowing who the aforementioned king is.

Another (big) hint - Sylvanas (the version before the HoF), Lord Jarr and my card have something in common.

Inb4 I would advise you to summarize each information you got out of the riddle. Try to answer the following questions:

- Which card has a weak body?
- Which card or what part of it is considered to be an antique? What does antique mean?
- What makes it unique?
- Who was the king, whom this card was used against?
- Which card has the potential to "summon" big minions "out of thin air"?
- "So my shadows away you took,/ Temporary is my fame/ in your little game." How popular is actually the card I'm referring to?

but still no

but gj, you are getting closer

warmer

Oh boy, I feel like jaws will drop, if people knew the real answer. 

Ok, so the card originates really from that era. You people are getting closer, but you aren't reading the King part correctly. No, this isn't a metaphor for Handlock nor for Face Hunter.

Last hint - if this wasn't clear enough, then I'm sorry, but look for an unpopular card, which was used in our battle against the aforementioned King.

Ring, Ring, Ring!

So my shadows away you took,                  - My (weird) way of saying, that the card is unpopular.
to give me a stargazing look,
but stop with this riddle,
as with me you only fiddle.
Temporary is my fame                                 - It was only mentioned in this riddle, but in-game you would never see it.
in your little game.
But fine, I will stay.

I may be weak,                                                -0/3 body
regarding my physique
but I'm an antique,                                                   - a card from the classic
I was there in your battle against the King          - it's The Lich King. People used it in their Big decks                                                                                                                                  (warrior, paladin...)
out of thin air big minions I can bring.                 - if the bot lives, it can swap itself with a big minion
I'm also unique.                                                       - no other minion has this effect. Madam Goya has a                                                                                                                               similar but not the same one.

ShadowBG - you are it. Davai.

Aaa ne. People hate my riddles. I won't forget the last time I tormented them with my riddle about Prince Taldaram. If you don't want to go, then someone else can make the next one.