You enter an old temple, from a long-dead religion. Before you, in front of a pile of riches, stands a statue of a creature made of a mineral dark as night: a woman's head, a lion's body, an eagle's wings outstretched to block your path. In front of it, a plaque written in old language -- but thankfully, you thought ahead to bring along a Universal Translator Mk. 7000! The plaque reads as follows:
Make a promise, if you'd like. But keep your word, else I may strike.
A set of words may do you well, a phrase with which you cast this spell.
Letters all, but not once each, this phrase to me you must beseech.
What do you say, to get your reward?