"Response: Cancel the effects of a response without an influence cost."

Can I cancel response of Joffrey Baratheon (kneel 3 influence or kneel 1 N character) when a player chooses to pay by kneeling noble character?

And what with cards like "A Pinch of Powder" when influence cost is irrelevant to first part of effect?

Rogue30 said:

- When an effect is written with a choice of either an influence cost or a "crest cost" and the controller chooses to kneel the crested character when initiating the effect, the influence cost essentially "goes away." The cost paid to initiate the effect, not any viable options that weren't taken, is the one that matters when checking the play restriction on "He Calls It Thinking." So yes, if a Noble was knelt, you could cancel Joffrey's Response with this event.

- The Pinch of Powder question is a little more complex. It comes down to a ruling that if for some reason, the "then" part of an effect cannot be initiated or resolved (for example, because there is no legal target for the effect), the part before the "then" can still be initiated. That seems to mean that in this case, even though the "then" part does have an influence cost and even if the player chooses to use it, the Response itself is initiated without an influence cost - meaning that "He Calls It Thinking" can cancel it. Other folks might not see it the same way, though.