One idea: Reverse Hangman. The players have to give a letter, and this adds to a word in front of them. When the word/phrase is completed? You're dead!
Oh, they'll try to cheat it. They'll guess their "q"s and "z"s early on. But then they run out of the rare letters, and things get interesting. They start to work out what the phrase is gonna be, and they keep trying to dodge around it, but eventually they have no choice. This does risk losing some of the suspense, though—by the time they reach the last letter, they'll know they're about to die before even guessing. You can mitigate this by not showing them where the letters are—"Yes, there is an x," you say, making a note on the hidden spaces. "Only two spaces left!"
If you can't think of quite enough many-lettered words, a few ways to extend it:
Each guess = one space filled. So, if you guess "a" for the phrase, "Apples Are Awesome", you would only fill in one of those three "a" spaces. The host has to let you know when you've gotten all the "a"s, of course.
Fractured Phrases: You actually go through a whole sentence, but you split up the rounds (so you can't guess for the end of the sentence until you've reached that point). Once you've guessed the first section, you move on to the next. For instance, you might guess for the phrase, "Dead men tell | no tales."