The cost of the ACE is discarding 3 cards. The card isn't worded consistently with most ACEs, but there's a parallel between what happens if it's successful and what happens if the opponent moves it (the most common way of doing so being DTTAH.) If you discard 3 for the ACE, and he DTTAHs it to remove it from your Ring, you get to fulfill the effect one more time before the card goes away, that being look, choose, and force discard.
And yes, carrying this over from the Discord, if you discard 3 to use it, and he DTTAHs you, you lose another two cards from your hand unless you have an effect that says otherwise. This is a VERY costly card.
EDIT: In fact, let's make this official right now. ERRATA: The ACE of Collegiate Champions now reads "ACE: When this card is in your Ring area, once during each of your turns you may discard 3 cards, and then look at your opponent's hand, choose 1 card, and he discards the chosen card."
The functionality of the card does not change, but the cost and effect need to be properly defined. This does so.