Instead of directly stopping creatures from attacking you, it forces your opponents to make a tough choiceeither pay they 3 mana for each attacking creature, or they let you create a 3/3 Ogre token for each one
What puts Memory Deluge ahead of its competition is the flashback ability it has
Play your first non-commander card after like nine turns of just putting down lands
Welcome Back, Slivers Spiders have always been lovers of keywords, with many of them having reach, deathtouch, or both
Other Blue decks in the format arent likely to have enough creatures of a single type to make it work though, so this needs a build around grade Giving all your spells flash is a decent upgradebut not usually one you want to spend an entire card on in Limited This is too expensive and by the time you play it, you wont have anything to put in play for free Unlike fellow Commander all star Smothering Tithe, Rhystic Study isnt completely unplayable, although it is still way worse in Limited than it is in Commander