The protection is odd and strong, basicallly none of the regualar instant and sorcery speed removal spells can target it, enchantments like O-rings can't target Emrakul, and haste creatures certainly can't damage it, so the main response to be concerned about is removal that doesn't target like a board wipe or edict
But as you can see, most of that feels pretty 2011
You can also imprint Mystical Tutor to allow you to find Nexus of Fate each turn, giving you a chance to have infinite turns
Mirko, Obsessive Theorist lets you return a creature from your graveyard to the battlefield, so long as that creature's power is less than Mirko's
Zenos yae Galvuss dragon flip mode is also fairly easy to pull off, as youll just need a Sephiroth's Intervention for its so-called friend. Seifer Almasy Rafiq-style double strike is a great start, but Seifer Almasy has plenty more to offer
When games only last 6-8 Turns and Mana Crypt is able to propel one player ahead in turns significantly, especially when paired with other mana rocks it makes for incredibly lopsided gameplay