Is it Autarch’s Gifts?
I don’t understand the first line but…
Two shall run amok (gives two artifacts)
both free and non foregin (artifacts are different from each other but of the Vet faction)
as the present often is (present is a play on words for gift)
Is it Zyx? summons 2 identical minions on random spaces
Yes it is 
Pay that before luck,
The number 7 is lucky, so paying that before luck is paying the number before 7. Autarach’s Gifts costs 6 mana.
Alright, I’ve got one now!
An impossibility made manifest,
speak my name, they’ll think you jest.
Weapons they hold dear, I arrest
They’re yours now, to put to test.
dude you are a master at riddles
Thank you, thank you! You humble me 
I still don’t know mmf’s though… maybe it’s Aspect of the Fox?
@degenerator Alright I’ll give, but you’ve gotta say please next time! The correct answer was aspect of the mountains
Reference to the need to wait until 6 mana cores to cast. The fate part is the idea that you change something into an elemental, therefore altering the life (fate) that it had, for better or for worse is up to how you use it.
When you cast the Spell the minion that transforms deals 5 damage to any nearby enemy minions (in most cases, killing them outwright). If you notice after the transformation, the elemental is made of ice and rock thereby ridding them of their fleshy parts (the asunder part came from the damage it deals to surrounding enemy minions and the fact that I imagine it to explode when turned) Notice that spells are cast, minions are summoned, and artifacts are equipped 
Aspect of the mountains can be cast from any position of the board on any minion(I neglected minions that cannot be targeted by spells, but it’s a haiku cut me some slack will ya?). The you is a minion.
Everything we know about @mmf 's riddle:
Edit: Woops, a few seconds too late xD. Nice job mmf
ha ha he just answered the riddle 
Nice one tho
What about Longshot405? i think it’s probably an artifact (weapon)
You probably would’ve gotten it in your next guess though
Welp, I was thinking about spells that transformed so I was fairly close. I just couldn’t find a card that seemed to fit all three lines without stretching too much.
Is it Grincherz?
An impossibility made manifest,
Not sure about this first line…
speak my name, they’ll think you jest.
Because Grincherz is named after a YouTube/Streamer (and the card is a little memey)
Weapons they hold dear, I arrest
They’re yours now, to put to test.
Gives you Artifacts from random factions
Either Alcuin Loremaster or Mindwarper based on the ability to give you your enemies spells. Or it could be Zenrui since no-one’s seen him since the nerf
Grincher is a very good guess based on the riddle. I honestly didn’t think about him when I made it. I’ll give you a point for that.
I’m afraid none of the guesses are correct thus far.
Could it be Mind Steal??? No one plays that card so its funny to even talk about it, also u steal a minion from your opponent
Also, a good guess. I’m afraid it’s incorrect though.
You are half correct!
Oh reaper of the nine moons?
It better not be dominate will, because I swear… Actually it might be reaper of the nine moons
It’s probably Rot9m, but I’m gonna guess Void Steal.
I’m afraid both are incorrect (Reaper and Dominate).
The last two lines are metaphorical, thus slightly misleading