The problem with Sliver Queen isn't so much the power but the accessibility to her
The Fall set is the rock, the foundation upon which the entire Magic year is built not just the last few years, but going all the way back to Mirage, the start of the annual structured block
Each were artist-signed and sold for over $500,000, with the latter being sold for roughly $800,000 to none other than Post Malone
That casting cost can be a bit prohibitive (splashing it in Limited won't be super easy), but in a White / Green build this 4/4 first striking, trampling construct hits hard
This card is powerful because it has the Forest type, making it fetchable with many spells that say search your library for a Forest. Another example is Tournament Grounds from Throne of Eldraine, which taps for red, white, or black mana but can only be used for Knight or Equipment spells (or colorless costs)
Night's Whisper might do much the same for your card advantage situation for the mana and it wouldn't becomes useless as your opponent consumed their hand but that is entirely overlooking the disruption caused by discard