ME1: Use Charm or Intimidate to resolve an impossible situation in the game.

Earning the Charismatic achievement will requires quite a few ranks in Charm or Intimidate.

You have two opportunities in each playthrough to earn the Charismatic achievement: One is during the mission on Virmire, where you’ll have to pass a Charm or Intimidate check during the confrontation with Wrex. Both of these options will require 8 ranks of Charm or Intimidate. The other opportunity is during the final mission of the game, Race Against Time. When you confront Saren in the Council Chambers, pass a series of Charm/Intimidate checks (you’ll require at least 9 ranks in either for this) to talk him out of a fight.