Wrong guess, though most of your reasoning is correct.

I descent on silent wings

I am one and many things

Fear my flame and fear my breath

Ignoring me will be your death

I think the Yeti-line refers to a minion which costs 4 and has worse stats than Chillwind Yeti. My first guess is Arathi Weaponsmith, although the line about the draft might imply that it's a neutral card so everybody can draft it.

Edit: We're also probably looking for a common, since the effect is "commonly" used.
Edit 2: If you're okay with that, I'd like to add Dark Iron Dwarf as my neutral guess.

Thanks for the list! I've never deleted my bomb warrior from before DoD because I had the feeling it was still competetive. Those upgrades look great! I'll give it a try this weekend.

Player History

- 1-1: Most of the times: no. I play for fun (on ladder nevertheless) and if I happen to like a T1 deck I see how far I can get with it. But no more try-hard-grinding after that one-time legend goal was achieved.
- 1-2: Dumpster Legend.
- 1-3: Rank 3.

- 2-1: Blackrock Mountain.
- 2-2: No.

- 3-1: No.
- 3-2: -

- 4-1: -

Standard

- 1-1: Yes.
- 1-2: Yes.
- 1-3: No.

- 2-1: Don't know, I don't play there.
- 2-2: Yes.
- 2-3: I feel like the game is harder, that is my opponents are better at the beginning of the month. That doesn't necessarily mean all of them are rushing for legend, though. I would rather say yes than no if you need a straight answer.
- 2-4: I don't know, I don't play there.

- 3-1: I play HS to have fun. For me this usually stops at rank 5. I don't like the grind that follows that floor.
- 3-2: Better rewards. Wouldn't it be fitting to reward a legendary for reaching legend? They could even make it a specific one for each month.

- 4-1: I have no idea what needs highly competetive players have. I guess making no difference between high legend and dumpster legend between months is very frustrating, though.
- 4-2: Haha, no way.
- 4-3: Apart from lacking skill? Time.

- 5-1: No.
- 5-2: -
- 5-3: -
- 5-4: Yes. I once participated in a private tournament, I liked that.

- 6-1: Yes.
- 6-2: The ranked floors improoved the experience a lot. For me, there is a clean line between fun-oriented people and really competetive players which is rank 5. It's easier to enjoy the game when you know what to expect. 

-7-1: (Re-?) Establish win streaks between 5 and legend to make it less of a grind.

Grandmaster, a new competitive format.

- 1-1: No.
- 1-2: No.
- 1-3: No.
- 1-4: No. (A major part of the format is the fact that you lose ranks when you don't play. I can't afford huge amounts of time to play every day and therefor I probably wouldn't play the format.)

- 2-1: 500.
- 2-2: 5 Euros.

- 3-1: Yes, if everybody had access to all of the cards. No if that was not the case.
- 3-2: Yes because meta shake-ups and killing OP decks is a good thing. No because that would feel extremely unfair to f2p players.

- 4-1: Yes.
- 4-2: They should be better than standard rewards, but not exceedingly so. Like standard gets normal cards, Grandmaster gets golden cards is okay, but rewarding hero skins other players could not obtain by other means would not be okay. A free ticket for next month if you finish above average would be nice, too.

- 5-1: Different laddering, I guess. Another cardpool would probably be not interesting enough.
- 5-2: Yes. Maybe like Arena without the drafting? Whoever loses a game gets eliminated and you can only play against opponents with the same number of victories. To adress lopsided matchups, opponents have to play best of three with three different decks and can't use any of them twice.

- 6-1: NO. (I'm not good enough.)

- 7-1: I find it really hard to come up with something genuienly new. Then there are a million different ways to play the game and interests which attract or don't attract the player base and potential new players. You've set yourself a real challenge here. My respect for that. Thanks for trying to make the game better!

Yes, that's all correct :-)

No, sorry.

Nope, but close in several places.

Here comes our next candidates tinder-bio! Would you swipe right?

Hot guy with a long tail is looking for a proud maid with cheap treats to destroy our enemies up to two at a time.

Oh my god. Now I get it. I misread Skydiving Instructor, it doesn't draw, but summon. Just leave me here.

Riftcleaver

Really nice idea, well done!

Deleted because of paramount stupidity.

Yes! You're next.

Alright, here's an easy one:

I'm a staple, I'm tier 1

Many games I have single-handedly won

Some people call me a spell on a stick

Surprising opponents gives me the kick

Sometimes I f* up Anduin without a single whack

If nothing else I provide you with a snack

Please don't send me to the hall of fame

Cause without me Hearthstone would be way too tame

Is it Treespeaker?

When it's time to rumble - it's a card from Rastakhan's Rumble

I won't ever mumble. - it's a treeSPEAKER, no mumbling here

My power creates mighty out of that which was humble, - buffing the treants into ancients

And before you leave your enemies will crumble! - no hint here, but "leave" is close to "leaf" which fits the druid theme

Pulled Nozdormu the Timeless from a pack yesterday. Since I'm still looking for Frizz and Ysera 2.0, I might yet get some packs and so haven't dusted it for now. So I created a new deck with only Nozdormu in it, pressed autocomplete and went to the ladder on rank 12.

In both of the first two games I managed to pull it off on turn 4 with a bunch of secrets active. On both occasions I ran into a Res Priest who kept spamming Zilliaxes / Convincing Infiltrators. Conceded on 8 in both games. I hate this archetype so much. 

Sorry, it was such a bad guess that I deleted it.

I second ArngrimUndyings reasoning for a HoF-card. My guess is Old Murk-Eye, who needs other murlocs to be effective.

Go ahead!

I don't think this will see much play. Could be interesting in tournaments though - nobody expects you to run that one. Might find a spot in control decks, just like Gnomeferatu.