Tasha's Famous Last Words

You speak a word of warning that foretells the demise of one creature you can see within range. While you are concentrating on the spell, if the target creature speaks aloud any words of any language, it must make a Wisdom saving throw or be reduced to 0 hit points. If the target creature fails this saving throw by 5 or more, then it is instantly killed.
The nature of the spell effect is based on the words that the target creature uttered to trigger the saving throw, and any resulting wounds or death magically dealt to them are done in as ironic a fashion as possible.

Tasha tipped her conical hat to the Red Wizard as he leveled a wand at her. "You would do well to point your wand in a different direction, Thayan, for I am in no mood for games. Speak again at your peril." Her booming words of warning echoed around her, clearly carrying the weight of a powerful enchantment.

The Red Wizard snapped his gaze all around the room, expecting demons to erupt from the walls. When several heartbeats passed in silence, he turned to her and grinned with blackened teeth. "This wand is your death, witch! And that is no game!!"

But no sooner had the Thayan uttered his retort than the Red Wizard was enraptured by the magic of Tasha's spell. He transformed, excruciatingly, bit by bit and piece by screaming piece into a set of bone-white playing cards. Tasha scooped up the cards and the accompanying skin-leather case, examining them with a dark smile. "Well my dear Thayan, perhaps I am in the mood for games after all."