Yang Zing Unleashed (MP15-EN117) [2015 Mega-Tins Mega Pack]

All monsters your opponent controls must attack, if able. During either player's Main Phase or Battle Phase: You can send this face-up card from your Spell & Trap Zone to the Graveyard; immediately after this effect resolves, Synchro Summon 1 Synchro Monster, using 1 or more "Yang Zing" monsters you control as Synchro Materials.