They're slightly larger than the card, and are designed to be used in conjunction with inner sleeves for the best possible protection
But we chose Clash Royale due to the simplicity of how building out your deck and battling it out works, much like how'd you'd approach any standard match in Pokmon's TCG
In this case its again about what motivates a player, and not the outcome - Spike will play land destruction if thats a powerful deck and doing so helps them demonstrate mastery over the metagame, but its a means to an end in that case, while a griefer will play land destruction for the experience of dominating opponents and preventing them from doing anything in a game - the power trip
Blue mages also care about control and proving themselves the smartest, and their primary method of defending themselves is by outthinking the opponent represented in-game with countermagic that proves they held the answer before the opponent considered the threat, and card advantage that symbolizes how much the blue mage has studied
Many will discuss the quality of the card, so Ill focus on what to expect price-wise
With Izzet Sleeves, you can focus on your strategy without worrying about the condition of your deck