Secret Gift is a Weiß Schwarz card from Love Live! DX Vol.2 LL/EN-W02-E028. Compare listings from Singapore Weiß Schwarz sellers on CardJio, then jio them on WhatsApp.
Choose a cost 0 or lower character in your clock with "Eli(絵里)" in its card name, and put it on any position of your stage. Choose one of your characters with "Eli(絵里)" in its card name, and that character gets +1500 power until the end of your opponent's next turn. Put this card into your clock.