An old school experienced DM insists Magic Missile always goes first. Does it or not, and why?

Question

A friend of mine is an experienced DM who started with D&D and then the AD&D 1st edition back in the day. I'm currently DMing AD&D Second Edition for him and he's playing a Wizard.

He has a firm belief that Magic Missile takes only one segment, is therefore instantaneous, and that speed is the point of the spell. When in a combat situation, if he casts Magic Missile but loses initiative, he protests, insisting that it only takes 1 segment to cast and is instantaneous.

I'm trying to explain this isn't the case, but I need back-up. Is he actually right? If he is or isn't, why is that the case? If it is not, I would like a concise list of references or point by point explanation of why that I can take to him. (He is stubborn, and will need that to change his mind.)

Answer 1

What you're looking for is the definition of the Casting Time entry in a spell's description, on page 129 of the Player's Handbook. (Segments are from AD&D 1st edition and aren't relevant if you're playing AD&D 2nd edition.) The relevant part on that page is:

If only a number is given, the casting time is added to the caster's initiative die rolls.

The caster rolls initiative, most certainly. (This is assuming you're using individual initiative, since it sounds like it, but that only affects the details, not the basic answer.) The casting time is how much slower the spell makes the caster, because once they start acting, they still need to start and complete the casting process. (It's worth noting that if they are hit between their raw initiative count and their initiative count + Casting Time, the spell is lost.)

Magic missile's spell description lists Casting Time: 1 (p. 136). Assuming for simplicity that no other initiative modifiers are involved, that means your friendly neighbourhood mage needs to roll 1d10 for initiative (per the Standard Initiative Procedure, p. 94) and then add 1 to find out when the magic missile casting completes. If the mage flubs the roll and the d10 comes up 10, that means the mage casting magic missile isn't acting until initiative count 11. That's likely last or close to it.

Magic missile is faster than most spells, but it doesn't overcome a mage whose reflexes are slow.

Even in 1st edition, initiative affects “beginning a spell” (1st edition PHB, p. 104). If that's the source of his confusion, he's misread or misremembered the rules, or perhaps mistaken an old house rule for an actual rule.

Answer 2

He's wrong even if you were playing 1e. He's still wrong in 2e.

In 1e a weapon with initiative beats ALL spell casting, if the spellcaster is in range (i.e., within 10ft/yrds for melee). Even if the spellcaster wins initiative a melee weapon may beat a 1-segment spell if the losing initiative (i.e., the weapon-user) rolls the same score as the weapon speed factor. So, if your magic user rolls a 6 and the guy with the longsword rolls 5, the sword still beats the spell.

Naturally, if the attacker has to spend time moving to get into range, then a 1-segment spell will generally be uninterruptible.

1e DMG pages 61-80 cover combat, but page 61 gives the basic outline and the following pages the details (I have a few blog posts on the subject, but start here if interested).