How does the Elemental Equilibrium work?

Hi there folks.

I kinda newbie at this game and have beed trying to construct a solid build for a elemental bow ranger recently. I've came up with this:
http://www.pathofexile.com/passive-skill-tree/AAAAAgIAAbwB5xBpFCAUcRiRGjgaVRvIJbwo-ilPKaUs6TCXMn4yiTLRNug5ijpSQapDMUVHTipQR1fiWfNbr14TYSFko2aecql07Xbnd-V65nzZgpuE75BVmK2bjZ7Nn8unMKeErKqvja-nr-u1BLZBuJPAGs6o037UfN0N37_kIudq6-7sOO969qP3Mve--Os=

The biggest question is how does the Elemental Equilibrium work if I attack with a mix of physical, cold and fire damage. Whick element is the priority? And does it even work? I'm going to change this build depending of how this game actually interpretates it. Before you call me a nobrain or something: for now it is not an actuall build, just a concept. I know there's too much int on the way, too much dmg compared to defense, etc, etc. I'll rebuild it after I'm sure how this game actually works :)

BTW: What do you think about grabbing a Vaal Pact? It may work nicely if I get some more defense. The leech from the total damage I'll have will do :)

Edit: After some research I found out that the avatar of fire absolutely ignores all types of damage except fire. Seems like I misunderstood that one and the build above goes to the bin. Topic question still actuall, but no build-related discussions. I need to work this out completely from the beginnig once again.

If you hit an enemy with an element, the enemy receives +25% to that element and -50% to the others.
To make use of this, you'll need to switch between elements with each attack.

Example:
Ice Spear -> Fireball -> Ice Spear -> Fireball -> ...
Glacial Hammer -> Infernal Blow -> Glacial Hammer -> ...

A hit with two elements will give the enemy +25% to both and -50% to the one left.
A hit with all three will result in +25% to all.