As far as Constructed is concerned, Ornamental Courage could be useful in some sort of aggressive Ally deck featuring Zada, Hedron Grinder. With Zada, you can target her with Ornamental Courage and it untaps all of your creatures and gives them the +1/+3 boost. However, in an aggressive deck, you're looking more for something like Titan's Strength, which gives the opposite +3/+1 boost. It also lets you Scry 1 for each time Zada copies it.
While this is definitely a good common, being more of a defensive type combat trick means it's probably not going to see much play outside of Limited.