I'm going to be a first-time DM in a few weeks DMing for some new players who will not necessarily be reading the rules. Because of this, I'm trying to get a good grasp on as much of the free material as possible.
My question is whether or not it is possible in combat to ready an action such as, "If an Archer fires an arrow at our wizard, move in front of them to block the arrow." This seems reasonable because they are simply moving. The Basic Player Handbook states the following for the action Ready.
First, you decide what perceivable circumstance
will trigger your reaction. Then, you choose the action
you will take in response to that trigger, or you choose
to move up to your speed in response to it.
In this case, the trigger is the fired arrow, and the action is movement. So the action seems OK, assuming they haven't used up their movement during their last turn.
My question is, as a DM, should I allow them to intercept an arrow and take damage instead? I think it might be important to say that we will not be using a grid for battle.
I think it wouldn't be unreasonable to have this be a valid action, and that they could take damage in place of the initial target; however, the rules about cover state:
if a target is behind a creature that gives half cover
which gives a character +2 AC and bonus on dex saving throws. Which leads me to believe that this would not be possible.
So I would allow the action to happen, but should it be resolved via cover or via an interception?
Best Answer
Readied actions happen when the trigger occurs, interrupting the initiative order. After the readied action takes place the rest of the action takes place as normal. In the case you mention, it is valid for one player to move in response to an enemy attack to give cover, given that he/she had readied the action (or has an ability that allows him to use a reaction in the same way).
Although I think he would efectively be giving cover to his ally, not taking the brunt of the hit, because the enemy would have been aiming at the ally, not the reacting player. It doesn't make complete sense, but it is that way according to the rules (they are in place to make thing easier and simpler, with as much realism as needed without being bothersome).
Your reacting player would give a +2 to AC to his friend. Then, by optional rules, if the attack doesn't hit the protected ally, but would have hit him if he hadn't the cover (the +2) it hits the cover. In that it would hit the reacting player, but it needs to surpass his AC to damage him.
It is a bit convoluted, so tell me if I need to clean up or clarify my answer.
And, of course, you are free as DM to change anything and allow the reacting player to completely protect his ally despite any rule I have commented ;)