There are three types of Dominion players. Some of us just play to unwind. Some play to compete. But then there are those of us who just want to watch the piles burn. Here's Messenger, for everyone who loves giving gifts and making merry.
Sometimes you'll get one for the Buy and coins. Sometimes it'll help you cycle your deck all the way down. But most of the time, you'll be using it to hand things out. Maybe your friend opened 5/2 and couldn't get two Ambassadors. Your Messenger purchase helps him with that. Maybe your opponent got himself a Potion and you feel like he should have another. Just be careful; you're getting one too. Maybe there's a sneaky way for you to win by making a bunch of Estates vanish at once. Messenger has you covered. Or maybe you're a jerk holding a Watchtower and you decide to hand out Curses in the most convoluted way possible. Man, what's your problem? Well, go for it, I guess.
The truth is, there are a lot of neat applications of the Messenger. I could go on and on about it, but I've had plenty of time to think about it, so I want you guys to have the fun. I'll leave you with one idea for your cousin's birthday party: try playing a 5 player game with this bad boy. (If you actually go and try that, please don't shoot the messenger)