Krosan Grip stops everything relevant except for Emrakul from the hand or the play of a second Omniscience. Whether you have the mana to cast grip after fighting over Show and Tell and playing your game plan is another question but if you have 3 mana untapped and grip in hand they're not going to kill you after Show and Tell resolves unless they have Emrakul already in hand. They can play a second Omniscience and put you on death's doorstep but Emrakul is the only thing that is going to kill you through split-second removal in response to their first play after Omniscience lands.