Both amendments are first-party from the pack's Rules Updates section, and one of them is a number rather than a rewrite.
Gift of the Prescient (20 points), changed from 3 inches to 6 inches. The mirror's text has this as a once-per-battle free Rapid Ingress targeting a GREY KNIGHTS TERMINATOR SQUAD unit from your army, which can then be set up more than 6 inches from all enemy units. The pack's change is consistent with that, and the enhancement is the only one in the faction that names a Grey Knights datasheet, so it is dead in a list without one.
That is worth knowing before you spend 20 points, and it is worth knowing about our catalog too: we track no Grey Knights Terminator Squad product that matches the datasheet exactly, so that unit is named and unlinked on this page rather than pointed at a near miss.
Truesilver Armour (1CP, Wargear), Effect section rewritten in full:
Until the attacking unit has finished making its attacks, each time an attack targets your unit, worsen the Armour Penetration characteristic of that attack by 1.
This is the same standardised rewrite the pack applied to the Alien Hunters card's Armour of Contempt in the same pass. The scope is until the attacking unit finishes, not until the end of the phase, so a second enemy unit shooting the same target gets nothing from it.
The other five stratagems are mirror-sourced: Hexagrammic Wards and Psybolt Ammunition (Wargear, 1CP), and Rites of Exorcism, Ritual of Warding and Steel Heart (Strategic Ploy, 1CP). The pack does not print them and we are not reproducing wording we cannot check. Read them in the Warhammer 40,000 app.
This card has no 2 Command Point stratagem, which is unusual: three of the other four Imperial Agents detachments have exactly one.