it's treads u silly.
anyway it adds ur movement speed, meaning u can chase heros faster,
or escape faster.
adds attack speed, meaning the enemy hero will die faster.
all these helps alot in the early part of the game, when the hp of
heros are not that skyhigh.
so getting the power treads first thing in the game does help u
silly.
p/s : it doesnt add to ur damage at all 