The main type of RNG found in this current expansion anymore is with cards that didn’t start in a users deck.
Other than that, you should know what decks contain what cards. That creates a scenario where you need to play around said cards.
You made it to legend and feel this way? Sounds like you’re 6k+ legend.
All of this is true without even mentioning the fact you jammed games with one of the most brain dead decks that literally tells you what cards to play. (The handbuff ones)