Champion Monsters and MVPs currently drop Titan Tokens, which are an in-game currency. These Titan Tokens may be vended, traded and put in storage. There is no way to get these tokens by donating. You must either kill the monsters, trade for them, or buy them from a Merchant or Super Novice shop.
10 Titan Tokens can be exchanged for a , which will give you a random costume headgear. To exchange your Titan Tokens for a Costume Egg, open the in your inventory, and choose Token Shop. The Costume Egg also has descriptions of the possible headgears you can get.
Additionally, there is an Old Costume Box you can get for 15 Titan Tokens; this contains a random previously released costume box, excluding the ones currently available.