Make animation play on enter invisable collider

I have taken the texture off of a cube and made it set for on trigger what im needing is to know how to make it so that when a player enters that area it plays an animation avalanch.

You got several options. Some of which are:

Use these to detect if the player is entering/is in the trigger:

OnTriggerEnter or OnTriggerStay

Use these to play the animation(s):

Animation.Blend, Animation.CrossFade or the most common; Animation.Play

There are of course more choices and approaches to this(these were merely suggestion).