Forum:Lyla question

Today I played against a lightsworn player and he summoned lyla and attacked my monster. After my monster got destroyed I thought that he would use her effect to destroy my field spell card but he said that he can't do that since he attacked with her and can't use her effect. Why would the fact that she attacked this turn prevent her from activating her effect? Can someone clarify? 93.139.113.217 (talk) 12:38, July 27, 2011 (UTC)