When Akroan Horse enters the battlefield, an opponent gains control of it.
At the beginning of your upkeep, each opponent creates a 1/1 white Soldier creature token.
9/15/2013 Akroan Horse’s enters-the-battlefield ability doesn’t target any opponent. In a multiplayer game, you choose the opponent as the ability resolves.
9/15/2013 In the last ability, “each opponent” refers to opponents of Akroan Horse’s controller. In most situations in two-player games, your opponent will control Akroan Horse and you’ll put Soldier tokens onto the battlefield.