You can literally dredge large numbers of cards into your graveyard every turn for zero mana but even if you dont want to tap out resources each turn filling your yard, the threat of doing it at instant speed should have every potential attacker thinking twice before tangling with the Wreath
Teferi, Time Raveler Teferi, Time Raveler shuts down instant and flash spells since opponents can now only cast spells at sorcery speed
It worked by playing lots of mana acceleration, rushing out Lich, pitching Autochthon Wurm to Nourishing Shoal and drawing lots of cards, playing Zuran Orb and sacrificing all of its own lands to draw some more cards, and hopefully drawing into enough mana acceleration to drop a win condition
Impulse draw is exiling a card and then being able to cast it for a short duration of time
Big spells are going to be very juicy for this, of course, but also small things like counterspells and other interaction will get the damage flowing
If you somehow control two copies of Katara, the Fearless, an Ally's triggered ability will trigger three times, not four
