Take a simple scenario as an example:
- A cleric casts sanctuary
- An enemy wielding a spear attempts to make a melee attack at the
cleric with his spear - The enemy fails his Wisdom save, and thus can't attack the cleric
Now what?
According to the sanctuary spell description:
On a failed save, the creature must choose a new target or lose the
attack or spell.
No one else is currently in melee range, but others are within move distance.
What happens to the enemy's intended attack, after failing the Wisdom save?
- Do they simply lose the attack if there is no other target
immediately in range, causing that spear attack to be wasted? - Does the enemy now get to "hold" the melee spear attack, use movement
to get in melee range with someone else, and then resume the same
melee spear attack on the new target? - Can the enemy choose to make a different kind of attack with the same
weapon, and decide to throw the spear instead (at someone else)? - Can the enemy choose to attack with a different weapon, such as a
shortbow, and attack someone else instead (either before or after
moving)? - Can the enemy choose to cast a spell instead of making a weapon
attack?
Best Answer
If no one else is in melee range, then there is no longer a valid target for the attack, and the attack is lost.
The description of the Sanctuary spell says (emphasis mine):
...not that the creature gets to change the attack or make a new attack.
The type or “method” of attack has already been chosen – a melee attack with a spear – and Sanctuary does nothing to change that. You can’t change the attack to a ranged attack with the spear, you can’t swap weapons and change the attack to a ranged attack with a bow, and you can’t suddenly decide to cast a spell.
As for "holding" the attack and moving so that you can attack another creature, you can’t do that either.
The PHB states the following, under "Breaking Up Your Move" (bold for emphasis mine):
Since this takes place during an attack, during an action, you’re unable to move.