leafeon gx pokemon card - 073/066 (073/066) [Grass][Colorless][Colorless] Solar Beam 110 Leafeon GX 13/156 Ultra Prism

Enchantment Underworld Breach Each nonland card in your graveyard has escape

The rewards vary, but usually, they unlock exclusive cards and cosmetics

In the later parts of games, when you have enough lands or if you are just flooding, these become spells you can cast and are not just dead in your hand

Some of them are inevitably better because of the guaranteed value of one of the cards required to meld, but thats an entire topic in itself

The allure of a mega-powerful 'Release Rage' fueled entirely by dead - sorry, discarded - Tatsugiri is clearly taking a toll on the market, as we've seen this guy sell for about as much as Gyarados ex