My 5e group just finished playing through the 5e Starter Set. I am currently a level 4 rogue that has specialized at level 3 as an Assassin. In the starter set I was able to pick up a Wand of Magic Missile (Starter Set) that lets me cast the spell Magic Missile using charges on the wand.
The Magic Missile (PHB) spell creates 3 darts that automatically do 1d4+1 damage to up to three targets at level 1 and makes an additional dart for each level following. Since there is no attack roll this spell normally has no opportunity to crit. However, the Rogue's Assassinate (PHB) skill says:
You have advantage on attack rolls against any creature that hasn’t
taken a turn in the combat yet. In addition, any hit you score against
a creature that is surprised is a critical hit.
If I use my Wand of Magic Missile against a creature that is surprised do I get to double the damage rolls? In other words, would using the wand to cast level 3 Magic Missile (max possible level from the wand) against a creature that is surprised do 10d4+5 damage to a single target?
Best Answer
No, critical hits must be linked with attack rolls.
I checked with Jeremy Crawford on Twitter and he says that critical hits must come from attack rolls:
You should read the full conversation between he and I to get more detail.
Critical hits come up in the PHB on pgs. 194 & 196. As I see it the PHB pg. 194 text doesn't imply that critical hits are exclusive to attack rolls:
PHB 196 describes critical hits but never uses the words "attack roll". Reading the text above someone new to DND could reasonably assume there are other causes of critical hits.
Despite this, Jeremy made it clear that the game designers intended critical hits and attack rolls to be linked.