Use Shared Fate to essentially swap decks with your opponent, giving them a deck that has no way to win.
The deck is as useless as possible after the swap. It can't do damage. It has no creatures. It can't destroy enchantments, so Shared Fate can't be removed.
Cards from Shared Fate don't go to your hand, and go to exile instead. This makes suspend cards useless after the swap, since cards are suspended from hand. Hand disruption also becomes useless, since you have no hand to take from. And the counterspells become worse on their own over time, since they become easy to pay for.
Shared Fate replaces drawing, so players can no longer be decked when it is in play. This means that games against mill often end in a draw.
Day's Undoing is a great follow-up to Shared Fate, since it empties your opponent's hand and lets you quickly draw deeply into their deck.
Sometimes, the opponent's deck just doesn't really work after the swap, and the only way you can win is by attacking with, say, a playset of Noble Hierarch. If we decided to run regular creature destruction, those games would end in a draw. That's why we only run creature removal that sends creatures back into the deck, so those games inevitably end in a win. I like having this guarantee, but dropping it can open the deck up to much better creature removal before the swap.
Panglacial Wurm is the only card in the format that can get through the lock once the swap is made and the boardstate is under control. I played against it, once, in a Battle of Wits deck, but it was not enough to save them.
