Ambush: You may put a card with the "Ambush" keyword into play from your hand as an "Any Phase:" action, by paying its gold cost with influence.
The word "paying" is throwing me off. I'm a bit confused as to whether or not there is a limited "pool" of influence like there is gold? If I have three influence and two Queen's Knight in my hand could I play them both with the three influence? The way it Ambush reads it sounds like I can. If that's the case Ambush seems very powerful, or am my missing something?