Goryo's Vengeance wants to reanimate Griselbrand or Atraxa via Goryo's Vengeance for an immediate haste-attack combo kill, so proactive disruption is key. Thoughtseize lets us strip their Goryo's Vengeance, Atraxa, or a counterspell like Force of Negation on our way to assembling our own combo. Ashiok, Dream Render shuts off their fetchland shuffles only incidentally, but its real value is milling them and exiling their graveyard, directly answering their reanimation targets before Goryo's Vengeance can find them. Fatal Push is weak here since their key threats (Atraxa, Griselbrand) are too expensive to hit, so it's cut for more proactive disruption.