Some small thoughts for fun things and stuff:

• In addition to Echo of Eons, I'm quite a fan of Time Spiral. It's not as abusable, sure, but untapping your lands is quite nifty. Given you have Narset, Parter of Veils in the deck, maybe you could also go for the Teferi's Puzzle Box lock with it...
• A "given" for me, in any monocolor deck, is going for the Extraplanar Lens strategy with snow-covered lands. You could also think now about Winter Moon, which seems like a lot of fun (for you).
• Mystical Tutor might be something I would prefer over Merchant Scroll, primarily because you can imprint it with Isochron Scepter and get lots of instants and sorceries. (On the other hand, you do have a lot of targets for Scepter...)
• In terms of zero-mana disruption, perhaps Commandeer and/or Misdirection are worthwhile. In a deck like yours, maybe Counterbalance could also be worth consideration, given how competitive decks have lower/more consistent mana curves (and you have Sensei's Divining Top...).
• Hurkyl's Recall seems also like a "fun" toy, especially in conjunction with Mycosynth Lattice, and given how artifact-heavy a lot of strategies/decks are...

Apart from a spate of tutors of varying price points (Vampiric Tutor, Mystical Tutor, Demonic Tutor, Entomb, etc.), here are some thoughts of varying degrees of evilness/making sure your opponents "love" you forever:

• Kokusho, the Evening Star is, for me, a must-include in any black-containing EDH deck, especially with how its life-drain effect scales with the number of players. You could also add an Archfiend of Despair and/or Wound Reflection to multiply suffering, Archangel of Thune to make your board bigger with every passing turn (or life-gain occurrence), and/or Boon Reflection for more life-gain fun!
• Some additional reanimation in addition to what you already have could be handy. For this, I would suggest Karmic Guide; Junji, the Midnight Sky; Reanimate; and/or Necromancy.
• If you have access to it, Yawgmoth, Thran Physician would be super-handy: on-demand sacrifice, not to mention card draw and weakening your opponents' boards.
• Some more land fetch/land thinning tools, like Expedition Map; Urza's Cave; Prismatic Vista; and Marsh Flats, might help. Similarly, Field of Ruin and Demolition Field serve double-duty of land fetch and land destruction for problematic lands. Alternately, some more multi-lands like Reflecting Pool, Mana Confluence, and other pain lands could help you in early game stages.

I just thought of a few other useful tools:

• Commandeer is another good zero-mana... not counter, but disruptor. It's become more popular, I've noticed, but it's still not something a lot of people see coming. Similarly, Misdirection is another handy tool for disruption, but it's more limited than Commandeer (though it's one less card to exile...).
• Teferi's Tutelage is another fun mill toy. It's a bit more limited than Sphinx's Tutelage, but why not double up the fun! Similarly, you can use Teferi's Puzzle Box to mill your opponents even faster while also disrupting their game play.
• Capsize is another all-purpose bounce, and reusable as well. Sunder is another great way to lose friends at instant speed. You could also consider Mystical Tutor to help dig for things you need.
• Clever Impersonator is more versatile than Copy Enchantment for one more mana, but it may not be extremely necessary.
• There are some lands that might be handy for your strategy. Oboro, Palace in the Clouds gives you reusable landfall; Boseiju, Who Shelters All makes sure your essential Instant and Sorcery spells don't get countered (e.g. Cyclonic Rift); Field of Ruin kills troublesome lands and gives mandatory search (and landfall), which is relevant for Archive Trap; and Academy Ruins is a more reusable Buried Ruin.
• Cyclonic Rift pairs very well with Memory Jar. Just saying. :P

Enchantress decks are always worthwhile. Looking at yours, here are some thoughts:

• My favorite enchantress is Argothian Enchantress: it's as fast as Sythis, plus the counterplay against a permanent with shroud is difficult for very many decks (I've noticed).
• In terms of fun enchantments, Greater Auramancy and Privileged Position are each an extra layer of protection for your board. Other enchantments of varying degrees of enchanted-ness are Abundance (makes a great combo with Sylvan Library); Smothering Tithe (given); Land Tax (you have the basic lands to support it, not to mention you also have land acceleration!); and Sphere of Safety (if you are in a combat-heavy playgroup). There, of course, is the classic Earthcraft/Squirrel Nest combo, but it's quite pricey (money-wise)...
• Enlightened Tutor is highly recommended for getting the important enchantments (and given you have lots of creatures that are enchantments, too...), maybe also with Worldly Tutor as more ways to get the key creatures you want/need/desire. You could also consider things like Eternal Witness and Regrowth for getting back things and stuff.

Some thoughts that immediately come to mind:

• A way of getting even more creatures as Braids fodder is Bitterblossom. I highly recommend it. You may also consider rejiggering the land base to make Field of the Dead worthwhile: you have enough lands to make it work, but more options to make it more feasible may not be a bad idea. You could also use things like Reassembling Skeleton to feed Braids even more.
• I know a lot of people don't like tutors, but tutors here can be quite handy. Vampiric Tutor, Demonic Tutor, Beseech the Queen, and Diabolic Intent are all possibly worthwhile. You could also consider some deck-thinning lands like Prismatic Vista and Fabled Passage.
• Mana-rock-wise, Mox Amber might be worthwhile.
• I vote Contamination for any mono-black deck. It's a great way to lose friends (which might be the point).