Whenever you cast a spell you dont own, put a +1/+1 counter on each Scout, Pirate, and Rogue you control.
Of course, this also depends on the utility of each creature you include
Aladdin Brave Rescuer can disrupt opponents who rely on items while Robin Hood Champion of Sherwood helps remove threats and gains Lore for doing so
Hideous Taskmaster is another expensive creature with middling stats, but is one of the better Threaten effects, as giving the temporarily stolen creature annihilator 1 and trample can be quite a scary proposition
Sword of Feast and Famine is definitely a favorite, too: The moody sky, the glowing moon, and the fact that you can untap all of your lands by dealing damage to an equipped creature make it viable just about anywhere
Summon the Painbow There is a lot of cross over for some five color legends among these categories, but I think most fit one over another