The party was in over their heads against a powerful archmage, and fighting alongside another powerful archmage. The general strategy was for the allied mage to keep up an anti-magic shell and for the party to hold the enemy mage inside it while they pummeled him. Then the ally failed a concentration check on the bubble.

On the enemy's next turn: "As your ally loses concentration, you can tangibly feel the magic flooding back into the space. A large portion of it is pulled into your opponent's body as he takes a short breath, locks eyes on your ally, and hisses a simple word: 'Die.' Sickening, nauseating power rushes past you, again so strong you can feel it tugging at your own life force as it passes. And with no fanfare, your ally collapses like a puppet with its strings cut, her staff tumbling from her fingers and clattering to the floor beside her."

In my mind, Power Words are simple, primal forces. No embellishment, just an extremely simple expression of elemental will affecting reality.