Rowdy is a keyword mechanic introduced with the Set 9: Doombringer set.
Rowdy powers trigger every time you play a card with cost higher than the Rowdy card’s cost. Then, the Rowdy troop gets its cost increased.
Let’s look at Shenanigator as an example.
Once Shenanigator is in play, when you play a card with cost 4 or more, he’ll trigger, drawing you a card and increasing his cost to 4. Then, you’ll be challenged to go over the top of that and play something with cost 5 or more… which will net you another card and push his cost up even higher! Each of the Rowdy cards end up being their own little mini game of seeing how many times you can cause them to trigger that delicious extra value. Of course, you can always revert them and start over from the beginning as well. This mechanic is perfect for the Merry Caravan as who loves games more than they do? Plus, it feels like a party that just keeps going.
Rowdy gives you big pay offs for curving out. The higher costs you can reach, the greater your rewards!