The key though is to assess which cards cross this threshold, as merely good rares arent worth twisting your mana base for
On the creature side, it's so expensive that you'll only realistically be looking to use it in something like Tron
When the evoke elementals were spoiled in Modern Horizons 2, people waxed lyrical about how broken Grief with Ephemerate was going to be, but in practice that interaction did not make any material impact on the format, and instead its been more commonly combined with Fury and Solitude in the Four-Colour Yorion, Sky Nomad decks
This usually involves sending them an itemized list of what you want to sell, engaging with one of their MTGO bots to actually send them the cards, and having them send you your payment through PayPal or some digital wallet
For any card printed since 1998, you have two clear indicators: The Set Symbol Color: The most immediate visual cue is the expansion symbol, located on the right side of the card, between the art and the text box