Visit Easter Bunny : During the Easter event time, players can visit Easter Bunny on the world map and receive Easter Bunny's gifts.
Whilst not technically a monster, because you don't kill these guys for rewards, you do still need to visit them to get rewards. They only appear during the Easter Festival Event (which as you would expect, occurs around Easter time) and are quite common on the server map.
A visit will cost you from 2 to 4 stamina (depending on the level of the bunny) and you can only visit an individual statue once. There is only a maximum of 3 claims per statue. And the rewards ... a Easter gift box with a chance of various rewards, dependant on the level of the bunny.