I still disagree. I think what you guys are thinking of, are cards in which one effect can be replaced by another effect, as Merrick says. But when that happens, the word "instead" is used in the text of the card. This is referenced in Comprehensive Rules under "response":
Typically, only one such response can be performed in a
given situation, because its effect will "prevent" that situation or replace it with another effect "instead."
As you can see, the rules differentiate between "prevent" and "instead." That's why at
Steward's Tomb you can still take burdens "instead" of wounds using The One Ring, but if you were trying to "prevent" the effect of taking wounds using a card, it would not work.
I also think there is a distinction in the rules between "prevent" and "cancel." "Prevent" generally refers to specific kinds of effects, whereas "cancel" is the only thing that does what you guys are talking about: Killing the card as a whole. That's why
Storied Homestead can stop
Shotgun Enquea at
Steward's Tomb, but
Narsil, Blade of the Faithful cannot. In fact, let's compare the wording of Narsil to
Too Great and Terrible:
Narsil:
Response: If bearer is about to take a wound, exert 2 Men to prevent that.
Clearly "that" is a pronoun referring to the effect of a wound that the bearer is about to take.
Too Great and Terrible:
Maneuver: Spot a Nazgul to wound Gandalf twice. The Free Peoples player may discard 2 cards from hand to prevent this.
Clearly "this" is a pronoun referring to the effect of two wounds that Gandalf is about to take.
Too Great and Terrible basically just has a built-in response action that is worded similarly to
Narsil, Blade of the Faithful. It isn't replacing one effect with another, it's attempting to "prevent" an effect. In this case,
Steward's Tomb shouldn't let you prevent this effect, because it says "Wounds cannot be prevented."
Again, if
Too Great And Terrible had read, "The Free Peoples player may discard 2
cards from hand to
cancel this," it would work at
Steward's Tomb. If the card had read, "The Free Peoples player may discard 2
cards from hand
instead of this," it would work at
Steward's Tomb. But because it specifies "prevent," it should not work at
Steward's Tomb.
"All cards do what they say, no more, no less."