@JeremyECrawford If rogue/fighter uses Action Surge to attack again on an attack with adv. Does he get sneak on both or just one?
— Hollesea (@Hollesea) February 8, 2017
Sneak Attack works only once per turn. #DnD https://t.co/gD8xmMtRjE
— Jeremy Crawford (@JeremyECrawford) February 8, 2017
What if I ready an action to strike someone when an ally attacks them and then action surge to take an action on my turn? I would then be attacking on my turn and on my ally’s turn(if they attack being my trigger to use the readied action)
Ready an action uses your reaction to complete and happens on the turn that was triggered. Therefore you used your sneak attack on a different turn than yours. When your turn comes again you may use a sneak attack once, no matter how many actions / bonus actions or reactions you take (on your turn) to attack an opponent.