Hellkite Courser is particularly bonkers with The Ur-Dragon since its whenever one or more Dragons you control attack trigger is amazingly powerful, as befitting a nine-mana Dragon Avatar
As for the sleeves themselves, they are functional but not exciting
If you have a 5/5 and an opponent attacks you, would you rather take 3, or take 5 and lose the ability to gain life
If you cast an Adventure spell from your graveyard this way, it's exiled as it resolves with the replacement effect created by the Adventure rules and you may cast the creature card from exile later
It has to be the best possible play when its the last card in your hand, letting you refresh and draw at least two new cards
Whether you prefer the more vibrantly detailed modern artwork or enjoy the simplicity of the most iconic vintage cards, these sets capture the best of every generation