Like the rest of the Ghost Eyecon line, you can use it in your DX Ghost Driver or to transform into Kamen Rider Ghost Shakespeare Damashii in the Ganbarizing arcade game. The said line of Kamen Rider Ghost shirts will go on sale starting on May 27th.
UPDATE (5/1/16): Fixed info on how to get the Shakespeare Eyecon. Special thanks to Sei Zha Kopp for the info.
[Source: The Ghouly News Tumblr]