FAIR USE DISCLAIMER As usual with these sorts of lists, Im more interested in capturing an interesting cross-section of powerful spells than I am in choosing a strict definition of what makes one best
Fierce Guardianship Paying 1 more mana for a Negate isnt the worst thing, but its bad enough to avoid play in formats like Legacy or Vintage
Each spirit-busting Collector Booster contains Rares and/or Mythics, Traditional Foils, Borderless cards, and Full-Art Lands
Search the Premises would be a suitable replacement for Smothering Tithe in more casual decks, and a decent supplement to it in more powerful builds
Legendary Creature Enchantment - God Thassa, God of the Sea Indestructible As long as your devotion to blue is less than five, Thassa isn't a creature
Frankly, this effect is much better in constructed than Commander