how would an encounter with multiple creatures with legendary actions work? do the creatures legendary actions occur simultaneously or can only 1 legendary action be taken per other creatures turn? No book here, but i would allow them all to use them. If more than one tried, resolve in initiative order

— Mike Mearls (@mikemearls) July 11, 2018

so say a dragons legendary tail attack, they would both occur, one after the other, at the end of another creatures turn? Yes

— Mike Mearls (@mikemearls) July 11, 2018