Casas paints large size oil canvases and Bic ball pen drawings where he reproduces images he takes with his camera, youthful and spontaneous domestic photographs of fleeting moments of nighttime fun.
During 2005 he participated, together with important artists such as Damien Hirst, Neo Rauch or Maurizio Cattelan at the International Biennial of Contemporary Art, Prague Biennale 2, Prague, Czech Republic) arranged by the Flash Art Magazine and curated by Giancarlo Politi. He was the only one Spaniard artist invited to that event. In 2006 he participated in The Sock Strategy exhibition at the 2nd International Biennial of Contemporary Art of Seville curated by Okwui Enwezor.
Casas also has won the very prestigious ABC Prize in Madrid, 2004. Also, he won in 2007, the grant from the Spanish Academy in Rome, Italy. He has exhibited at some of the most important galleries in Spain and at the international art fairs of Chicago, Miami, Palm Beach, México, Bogotá, London, New York, Basel and Madrid. His work can be found in important collections and museums like the ARTIUM (Basque Museum of Contemporary Art) where he also participate in the collective exhibition Catharsis, with such important artists as Miquel Barceló, Antoni Tapies and Antonio Saura. He is considered one of the more influential young painters in Spain.