Does a Readied action extend into another round?

Question

Had a 5e session today, with a player wanting to delay his turn. Since Delay was removed and Ready was the closest option, we tried to use it. In this situation his trigger action was to wait until the cleric could heal him, then he would run to another location.

Unfortunately the cleric had already taken an action for the turn, meaning it couldn't trigger until the next round, so he was faced with standing in the fray, within a breath of death, creatures still able to attack. Since he can't change his initiative order with Delay anymore, we would like to know if a Readied action will extend into the next round?

Answer 1

Readied actions last until the start of your next turn, which means yes, they extend into the next round of combat. As per the PHB errata:

Ready (p. 193). You have until the start of your next turn to use a readied action.

So regardless of whether the cleric has already acted this round, the Readied action would still carry over into the next round and trigger when the cleric heals the other player that round, so long as it's done before the start of the other player's turn.

Answer 2

When you Ready an action, the text says it is used as a Reaction later in the round. This does not mean that the Readied action is lost at the lowest initiative value though. Rather, the action is not wasted unless their next turn comes up a full round later.

The Player's Handbook Errata makes specific mention of the Ready action, specifying that "you have until the start of your next turn to use a readied action."

Answer 3

The Ready action makes no mention of rounds (PHB Errata p.193):

You have until the start of your next turn to use a readied action.

That is you can use the readied action any time between now and your next turn: somewhere in that period the cleric is bound to have a turn and could use it to cure him triggering the readied action. Or he might not and the action is lost. Indeed, the players and DM will know exactly within the initiative order this will (or won't) happen.

You need to remember that round is an interval of time with no fixed start. Specifically, a round is the period of time from a creature's turn to their next turn so if there are 12 creatures in the combat there are 12 overlapping rounds all going on simultaneously.