Mad Bunny Shield Event is ON!
Learn all about how you can participate here!
Speak to the Mad Bunny Merchant in Prontera next to the Silvervine NPCs 
There are 2 options:

The first option allows you attempt to add a slot to a guard, shield, or buckler for 25 Silvervine. Each attempt to slot is a 5% chance.

The second option will automatically change any slotted guard, shield, or buckler into a Mad Bunny style shield for 400 Silvervine. This is a 100% chance at the Mad Bunny Style Shield.

If you choose the second option, make sure your item is equipped first. Your guard, shield, or buckler also needs to be slotted in order to change it into a Mad Bunny style shield. Please note, the refine level will be kept but any cards equipped to the item will be lost upon the change. This is a Mad Bunny style shield, a cosmetic-only change.

Ta-da!