after a lot of searching for the optimal deck in standard and inspired by the deck of ObZenHS (see in comment) i managed to get my first time standard legend rank.
The deck is very expensive so I wouldn't go crafting the cards before you try out the deck to see if it is something for you.
Possible replacements for the legendary cards:
Taelan Fordring - the card on itself isn't really that impressive in the first place, but in the combo with Oracle of Elune and Razormane Battleguard can lead to an early GG just from the psychological effect to the opponent where you can draw your big minion to more board presence and draw
Possible substitute same as Greybough
Cornelius Roame - you got to be very careful while playing this card if you really craft it, because the draw effect might be overwhelming in combination with Encumbered Pack Mule leading to a fast overdraw, but it is a good way to fill the minion with your Vibrant Squirrel seeds if your board is not full and draw for your combo cards
Personally I see it as essential, but the substitutes can be the same as for the other 2
Both the epic cards are essential, so if you don't have them, it is best to stay away from the deck
I have to say I started playing this deck at Diamond 5 and managed to get legend after 20 games(16-4) with a winrate of 80%
played 5 games against mages of which one without quest(I was shocked tbh) and went 3-2
I didn't play a single game against warlock in the 20 games
Have fun all