If “Imperial Order” & “Necrovalley” are both active, and “An Owl of Luck” is flipped, you add the card to your hand because “Necrovalley” is face-up on the field, even though its effect is negated.
If “Mystical Space Typhoon” is chained to the effect to destroy “Necrovalley”, so that “Necrovalley” is not on the field when this effect resolves, you cannot place the card in your hand.
You select the card for this effect when the effect resolves, not when it activates.