Given that:
A: Boardwipes are strong in a 4-player format,
B: The card pool we have to work with is so massive that any given deck will have access to boardwipes that synergize with their deck in a way that breaks parity,
Corollary to B: The card pool we have to work with is so massive I can never remember them all,
I decided to make a categorized list of boardwipes for any given EDH theme. I've been working on this list off and on for the last week, and I have an itemized and thoroughly tagged text document, but I decided to also upload the list to Archidekt & categorize it there as well.
https://archidekt.com/decks/22143315/boardwipes
This list is a work in progress, by no means exhaustive, and is probably still full of errors and inconsistencies - I initially built it just for my own use - but I think it could be helpful for others' deckbuilding efforts, so take a look and let me know if I'm missing anything.
A few notes:
*Make sure to sort by "Categories (Multiple)", as many of the cards are in multiple categories; the number of categories is signified by the card's quantity.
*I generally avoided vanilla sweepers (Day of Judgment, Damnation, Blasphemous Act, etc) and effects that deal less than 5 damage to all creatures.
*I only included effects that sweep creatures (sorry Bane of Progress), but I did make sure to make note of the effects that hit all Nonland Permanents or all Creatures + Enchantments + Artifacts.
*I put spells that specifically hit creatures and artifacts (but not enchantments) under enchantment synergies, and spells that specifically hit creatures and enchantments (but not artifacts) under artifact synergies.
*I didn't include any effects like Obliterate or Cataclysm that could be considered Mass Land Denial, but I did include some effects that might be a grey area in that regard (e.g. Urza's Sylex).