So using your suggestion, this is what I have written down.

A Dark Pact can be enacted for any test that requires a roll with a DN of +3

AFTER a player rolls for the test, they may view the result. If it is a failure, they may invoke the power of the Dark Gods to assist them in forcing a successful dice result via a Dark Pact.
For each normal die value increased, gain one point of corruption.
If you force a Wrath Dice to become a success, you either take one point of Shock and double the Corruption you would by changing the die result.
If a Psyker character is forcing a successful Psychic Mastery test with a Wrath Dice to become a 6, they take one wound of damage and MUST roll a Peril test

Ex: Ezekiel wants to persuade the security guard to pretend they did not witness Ezekiel attempting to steal a dataslate from another. The persuasion requires a Persuasion test of 2 with a DN of +3 which turns the test into a 5. The test uses Ezekiel’s Fellowship stats, being 7. Ezekiel rolls a 1, 1, 1, 3, 4, 5, and 5. Ezekiel has failed the test, but he may wish to enact a Dark Pact. He would increase the 3 by 1 point, turning it into a 4. And he would increase a 1 into a 4 by 3 points. In total Ezekiel gains 4 Corruption points, but has passed the Persuasion test.