Gem Shield is able to get rid of four gems in total, rather than just three, but it only does that if you actually have incoming gems and gems in your gem pile. The “top” mechanic lets you manipulate that drop pattern which frees you to buy the card you want without it backfiring by leaving an easy drop pattern behind. You can’t let them get three purples in a row or something. When you choose which card to buy from the bank, the pattern of colors you leave behind is the pattern that will fall into your next opponent’s gem pile. If you have a way to draw a card, that lets you potentially play that card on the same turn, but the real thing it teaches you is about drop patterns. It also has the “top” icon which lets you put a card from the bank on top of your deck. Effortless Block has even more benefit over the basic block than a 0-cost though. These blocks cost 0 actions which makes them a heck of a lot easier to fit into your turn.
