Let's say that I {pillar of flame} a {niblis of the breath} can my opponent activate it's ability and put it on the stack to resolve before my pillar will? Or is there another priority system established for this. It was just brought to my attention that tapping a creature with {niblis of the breath} ability does not negate the attack of an opposing creature. Therefore something doesnt go onto the stack like I thought it would because if it did, the attacking creature would tap before declaring it's attack
Also, could I tap a creature that an opponent is about to attack with before he attacks with it?
Yes, the ability will go on the stack and resolve before he dies.
If you plan to tap an opponent's creature so he can't attack with it, you need to do that before the declare attackers phase.
Right. Declaring attackers doesn't use the stack.
The Begining of Combat step is the last chance to tap a creature before it attacks. After that is the Declare attackers step and the first thing that happens is, you guessed it, they declare attackers. By then it's too late.
So, really, theres no way to know if they are going to attack with it or not before you tap it.