The Set Unit Animation by Index Function
Unfortunately but not surprisingly Blizzard forgot to put the Set Unit Animation by Index into GUI. This means you have to use the Custom Script Action. You could also use World Editor Unlimited by Pitzermike which has the Set Unit Animation by Index as an added action.
The function basically allows you to play ANY specific animation for a unit. It doesn’t take into account any strings or “rare” and “common” values, it just takes into account an Integer which is the number of the animation. The problem many people have with this function is that the order of the animations is NOT the same as the order in the Model Viewer inbuilt into WE. This is because the WE viewer automatically re-arranges the animations into the “stand”, “walk”, “attack”, “death”, “decay”, “dissipate”, “morph” and “birth” order.
In order to determine which Index to use, you can use Warcraft 3 Viewer. Open the model in Warcraft 3 Viewer and open the Treeview Window (CTRL + H). In the Animation section you will see the various animations, the order in which they are in is the same as the Integer you would use.