D&D 5E Spell conversion: Mordenkainen's force missiles?

Quickleaf

Legend
Trying to convert a spell from 2e and 3e called Mordenkainen's Force Missiles, staying true to the original but also making it unique from just upcasting Magic Missile in that it can also be used to very briefly punch holes in magical force barriers.

Have you tried converting this spell yourself or seen it converted elsewhere? Does my version look reasonable or any suggestion on how you'd adjust it? Are there interactions with other class features I should consider?

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Mordenkainen’s Force Missiles
4th-Level Evocation (Sorcerer, Wizard)
Casting Time: 1 Action
Range: 120 feet
Components: V, S
Duration: Instantaneous

You create a glowing globe of magical force that streaks forth and hits a creature or force barrier of your choice that you can see within range, before exploding in a burst of force. Against a creature, the globe deals 2d4+2 force damage, and then deals 1 force damage to each creature within 5 feet of the target.

A creature protected by the Shield spell or wearing a Brooch of Shielding is immune to this damage. Also, resistances and immunities to Magic Missile apply to this spell in the same manner.

Alternately, you may use the globe to strike a force barrier created by a spell, such as a Forcecage or Wall of Force. Create a temporary 2-foot-diameter hole in the barrier that lasts until the end of your current turn, large enough for a Medium creature to squeeze through. You may create another such hole or widen an existing hole’s diameter by 2 feet per globe used against the force barrier.

At Higher Levels. When you cast this spell using a spell slot of higher level, the spell creates one more globe for each slot above 4th level. The globes strike in sequentially and you can direct them to hit any combination of creatures and force barriers.
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Notes:
  • "Punching through force barriers until end of your current turn" is meant to allow an upcast Mordenkainen's Force Missiles to punch a hole with first missile, then fire other missiles through. It might be used with bonus action cantrips, the caster teleporting or moving through the hole, or an ally who Readied an action/move to exploit the hole. It's mean to provide more flavor to the spell, evoke that fantasy of a force field being (momentarily) pierced, and also provide one possible countermeasure to force barrier spells that sorely lack countermeasures.
  • Single target damage should be less than Magic Missile, but might be TOO low when not upcast. Not sure. I think there are "pile-on" / circumstantial benefits to being able to plink more creatures with damage – e.g. forcing Concentration saves, and maybe some class feature interactions but not sure on those yet.
  • With more targets, the more effective the spell gets. Likewise, the more globes (i.e. upcasting), the more effective the spell gets.
  • I want the spell to play fast, and so I choose to eschew requiring additional targets to make saving throws (which previous editions required), making it auto-damage like Green Flame Blade.
  • Orange indicates when damage equals or exceeds Magic Missile.
  • Damage should mostly remain equal to or less than the DMG Spell Damage guidelines for a multi-target spell. Red denotes where this breaks down.

LevelDMG Spell Damage (multi-target)Magic Missile DamageForce Missiles Damage - no addt'l targetsForce Missiles Damage - 1 addt'l target per globeForce Missiles Damage - 2 addt'l targets per globeForce Missiles Damage - 3 addt'l targets per globeForce Missiles Damage - 4 addt'l targets per globeForce Missiles Damage - 5 addt'l targets per globe
4th24.5 (7d6)21 (6d4+6)7 [(2d4+2)]8 [(2d4+2+1)]9 [(2d4+2+2)]10 [(2d4+2+3)]11 [(2d4+2+4)]12 [(2d4+2+5]
5th28 (8d6)24 (7d4+7)14 [2 * [(2d4+2)]16 [2 * (2d4+2+1)]18 [2 * (2d4+2+2)]20 [2 * (2d4+2+3)]22 [2 * (2d4+2+4)]24 [2 * (2d4+2+5)]
6th38.5 (11d6)28 (8d4+8)21 [3 * [(2d4+2)]24 [3 * (2d4+2+1)]27 [3 * (2d4+2+2)]30 [3 * (2d4+2+3)]33 [3 * (2d4+2+4)]36 [3 * (2d4+2+5)]
7th42 (12d6)31 (9d4+9)28 [4 * [(2d4+2)]32 [4 * (2d4+2+1)]36 [4 * (2d4+2+2)]40 [4 * (2d4+2+3)]44 [4 * (2d4+2+4)]48 [4 * (2d4+2+5)]
8th45.5 (13d6)35 (10d4+10)35 [5 * [(2d4+2)]40 [5 * (2d4+2+1)]45 [5 * (2d4+2+2)]50 [5 * (2d4+2+3)]55 [5 * (2d4+2+4)]60 [5 * (2d4+2+5)]
9th49 (14d6)38.5 (11d4+11)42 [6 * [(2d4+2)]48 [6 * (2d4+2+1)]54 [6 * (2d4+2+2)]60 [6 * (2d4+2+3)]66 [6 * (2d4+2+4)]72 [6 * (2d4+2+5)]

Mordenkainen's Force Missiles
Level:
4
School: Invocation/Evocation, Force
Components: V, S
Range: 30 yds. + 10 yds./level
Save: Special
Casting Time : 4
Duration: Instantaneous

This spell creates a brilliant globe of magical energy that streaks forth from the caster’s hand to unerringly strike its target, much like a Magic Missile spell. The subject must be seen or otherwise detected in order to be targeted by this spell. The wizard creates one missile at 7th level and an additional missile at every third level after 7th—in other words, two missiles at 10th level, three at 13th, four at 16th, and so on, to a maximum of seven missiles at 25th level. Each missile inflicts 2d4 points of damage to the target and then bursts in a 3-foot radius concussive blast that inflicts 1 point of damage per level of the caster—for example, a 12th-level wizard could conjure two force missiles, each of which strikes for 2d4+12 points of damage. The victim may attempt a saving throw vs. spell to negate the concussion damage, but the impact of the missile itself allows no saving throw. Just like Magic Missile, the force spheres may be directed at as many or as few targets as the caster likes. The missiles can easily damage or destroy inanimate objects, especially fragile or delicate items.

Mordenkainen's Force Missiles
Evocation [Force]
Level: Sor/Wiz 4
Components: V, S
Casting Time: 1 action
Range: Medium (100 ft. + 10 ft./level)
Targets: Up to four creatures, no two of which can be more than 20 ft. apart
Duration: Instantaneous
Saving Throw: None or Reflex half (see text)
Spell Resistance: Yes

You create a powerful missile of magical force, which darts from your fingertips and unerringly strikes its target, dealing 2d6 points of damage. The missile then bursts in a 5-foot blast of force that inflicts half this amount of damage to any creatures in the area (other than the primary target). The primary target is not entitled to a saving throw against the burst, but creatures affected by the burst may attempt a Reflex save for half damage.

If the missiles' burst areas overlap, secondary targets make only one saving throw attempt (and only one SR check, if applicable). A character can be struck by one missile (or more) and also be caught in the burst of another missile. In such a case, the character may attempt a Reflex save to halve the burst damage, and SR might apply.

The missile strikes unerringly, even if the target is in melee or has anything less than total cover or concealment. A caster cannot single out specific parts of a creature. The spell can target and damage unattended objects.

For every five caster levels, the caster gains one missile. A caster has two missiles at 9th level or lower, three missiles from 10th to 14th level, and four missiles at 15th level or higher. A caster can make more than one missile strike a single target, if desired. However, the caster must designate targets before rolling for SR or damage.

Mordenkainen's Force Missiles
Evocation [Force]
Level: Sorcerer 4, Wizard 4
Components: V, S
Casting Time: 1 Standard Action
Range: Medium (100 ft. + 10 ft./level)
Target: Up to four creatures, no two of which are more than 30 ft. apart
Duration: Instantaneous
Saving Throw: None
Spell Resistance: Yes
Sparking bolts of blue magic, like giant magic missiles, streak from your outstretched hand to strike your foes and explode in sparkling bursts.

You create powerful missiles of magical force, each of which darts from your fingertips and unerringly strikes its target, dealing 2d6 points of damage. The missile then explodes in a burst of force that deals half this amount of damage to any creatures adjacent to the primary target.

The missile strikes unerringly, even if the target is in melee or has anything less than total cover or concealment. A caster cannot single out specific parts of a creature. The spell can target and damage unattended objects.

You gain one missile for every four caster levels. You can make more than one missile strike a single target, if desired. However,you must designate targets before rolling for spell resistance or damage.
 
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cbwjm

Seb-wejem
When I converted it, I gave it the following
  • Create 3 missiles that strike for 2d4+2 force damage.
  • Missiles explode (5ft radius) for another 2d6 force damage (dex save negates). Only take damage once if caught in over lapping explosions.
  • +1 missile for each level above 4th.
This puts maximum damage at 4th level if targeted against a single target at 42, the same as the multiple target damage. I think this is fine since they hit automatically.

Shield doesn't block the missiles, but I wouldn't really be opposed to adding that to any autohit spell.

I like your addition of punching through barriers though, that's a cool feature.
 

Ancalagon

Dusty Dragon
A few comments

1: Only one missile at level 4? That is very weak damage
2: On the other hand, 2d4+2 scaling per level is preeety good
3: splash damage of 1? Why even bother? Either give it more spash oomph, or don't bother.
4: The real utility of this spell (due to the paltry damage) is punching temporary holes in force barriers. Given that, the very limited punch (2 foot hole that only works on your turn?) created is reaaaly limited

So I would recommend adding a bit more damage to the base spell, slow the scaling to compensate (maybe one missile per 2 level, remove/boost the splash, and think more about the barrier breaching potential... because that' the real "special" thing here. It needs to be a bit better, but not TOO much because it then invalidates those spells.
 

Quickleaf

Legend
A few comments

1: Only one missile at level 4? That is very weak damage
2: On the other hand, 2d4+2 scaling per level is preeety good
Yeah, the maths need work. It needs to be stronger when just one missile is cast, but probably shouldn't scale as intensely.

3: splash damage of 1? Why even bother? Either give it more spash oomph, or don't bother.
Sure, I was hoping other folks more knowledgable than me about PC class builds could chime in about boosts a PC could potentially get to the spell that might make the minor splash damage more potent... I feel like there is something there but I can't recall it atm...

Anyhow, the original spell has the bolts explode as part of its flavor & effect, so I do want to retain that. Not sure how much damage the splash should be though?

For ex, my first draft had the initial damage as 2d4+spellcasting mod, and then the splash to adjacent creatures = spellcasting mod. However, that ended up kicking the damage closer to the red zone with upcasting even more than is already happening.

4: The real utility of this spell (due to the paltry damage) is punching temporary holes in force barriers. Given that, the very limited punch (2 foot hole that only works on your turn?) created is reaaaly limited
Yes, I kept the utility high and damage low. To rein in the utility, I could stipulate an even shorter window of opportunity, such as: "Each hole closes as soon as another spell effect, attack, or creature passes through it. Otherwise any holes close at the end of your current turn." That's still a little ambiguous (does a missed attack pass through it or not?), but at least that way it's only allowing one thing, like only the follow-up force missiles, or only one of the Ranger's shots, or only one PC to slip through. Unless it's upcast.

For ex, wall of force is 5th level. That's part of the reason why I have 4th level force missiles only create one globe/missile. That way the caster PC by themself can't really get much use out of it (barring specific builds) until they upcast it at 5th level (i.e. equal to wall of force), which kinda mirrors how dispel & counterspell work.

So I would recommend adding a bit more damage to the base spell, slow the scaling to compensate (maybe one missile per 2 level, remove/boost the splash, and think more about the barrier breaching potential... because that' the real "special" thing here. It needs to be a bit better, but not TOO much because it then invalidates those spells.
Thanks your critique and suggestions, Ancalagon!
 

EzekielRaiden

Follower of the Way
Loath as I am to give excessive power to Wizards...I'm afraid I have to agree with Ancalagon. 2d4+2 damage is weak. Per the DMG, a typical spell of level 4 should do 6d10 damage if it targets a single creature, or 7d6 if it targets multiple creatures. A first-level spell should do 2d10 single-target (save for half) or 2d6 multi-target (save for half.) If the spell deals no damage on a save, you can increase that damage by 25%. Presumably, then, if the spell always does damage, reducing it by some percentage is appropriate. E.g., compare magic missile to a spell of equal level:

Magic missile: 1d4+1 per spell level, nice damage type. 3.5 average damage per missile.
Chromatic orb: 3d8 (+1d8 per spell level upcast), ranged spell attack (no miss damage, can crit), flexible type. 13.5 average (+4.5/level upcast)
Thunderwave: 2d8 (+1d8 per spell level upcast), AoE save for half, push effect on fail. 9 damage average (+4.5/level upcast)
Hypothetical standard spell: 2d10 (+1d10 upcast), save for half. 11 average damage (+5.5/level upcast.)

So magic missile is 3.5/11 = 0.31818... or about a third of the hypothetical standard spell. Chromatic orb is 13.5/11 = 1.22727..., which is reasonably close to being 25% more damage, especially if you factor in crits. So we can say, with reasonable certainty, that the damage penalty is around "reduce to 1/3."

So, a hypothetical standard 4th level spell does 6d10 = 33 average damage. Reduce this by 1/3 to get approximately 11 average damage. 2d4+2 is only 7. You would need no less than four targets within 5 feet to compensate for the loss, which is unrealistic in the vast majority of situations.

My recommendation, then, is to have the missile "ricochet" to a nearby target. First hit does 2d4+2, second 1d4+2. Any ricochet must hit a target other than the original target, but if cast at levels above 4th, all ricochet missiles can hit the same target. IMO, the powerful scaling is sort of the point of these spells; they are weak but reliable at low spell levels and surprisingly potent at high levels. You can't fire more than 6 missiles with this spell, which would deal 69 (nice!) average damage, split between two targets. This is noticeably less than the average 49 (save for 24) damage per target of the 9th level AoE spell weird, which can target more than two targets--expect typically ~74 damage for two targets (one saves, one fails.) To say nothing of more powerful ones like meteor swarm (which does a whopping 20d6 damage even on a failed save.)

This produces a total damage of 3d4+4 = 7.5+4 = 11.5, very slightly above average for an "auto-hit" spell but spread out between two targets so it isn't that powerful (it's always better to concentrate fire.) When coupled with the "shield or shielding brooch" limitation, I think that's enough to justify being slightly better damage than magic missile on top of having the barrier-cracking utility.
 
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Quickleaf

Legend
I seem to recall some crazy magic missile builds that actually worked (as opposed to those abusing / misinterpreting semantics with spirit shroud & hex), but for the life of me I can't find them now. I was hoping to look at those when fine-tuning the damage this spell deals, just so I don't make something waiting to be broken.
 

EzekielRaiden

Follower of the Way
I seem to recall some crazy magic missile builds that actually worked (as opposed to those abusing / misinterpreting semantics with spirit shroud & hex), but for the life of me I can't find them now. I was hoping to look at those when fine-tuning the damage this spell deals, just so I don't make something waiting to be broken.
Perhaps remembering a different edition (or PF or the like)--hex requires attack rolls, which magic missile does not have.
 

Quickleaf

Legend
Loath as I am to give excessive power to Wizards...I'm afraid I have to agree with Ancalagon. 2d4+2 damage is weak. Per the DMG, a typical spell of level 4 should do 6d10 damage if it targets a single creature, or 7d6 if it targets multiple creatures. A first-level spell should do 2d10 single-target (save for half) or 2d6 multi-target (save for half.) If the spell deals no damage on a save, you can increase that damage by 25%. Presumably, then, if the spell always does damage, reducing it by some percentage is appropriate. E.g., compare magic missile to a spell of equal level:

Magic missile: 1d4+1 per spell level, nice damage type. 3.5 average damage per missile.
Chromatic orb: 3d8 (+1d8 per spell level upcast), ranged spell attack (no miss damage, can crit), flexible type. 13.5 average (+4.5/level upcast)
Thunderwave: 2d8 (+1d8 per spell level upcast), AoE save for half, push effect on fail. 9 damage average (+4.5/level upcast)
Hypothetical standard spell: 2d10 (+1d10 upcast), save for half. 11 average damage (+5.5/level upcast.)

So magic missile is 3.5/11 = 0.31818... or about a third of the hypothetical standard spell. Chromatic orb is 13.5/11 = 1.22727..., which is reasonably close to being 25% more damage, especially if you factor in crits. So we can say, with reasonable certainty, that the damage penalty is around "reduce to 1/3."

So, a hypothetical standard 4th level spell does 6d10 = 33 average damage. Reduce this by 1/3 to get approximately 11 average damage. 2d4+2 is only 7. You would need no less than four targets within 5 feet to compensate for the loss, which is unrealistic in the vast majority of situations.

My recommendation, then, is to have the missile "ricochet" to a nearby target. First hit does 2d4+2, second 1d4+2. Any ricochet must hit a target other than the original target, but if cast at levels above 5th, all ricochet missiles can hit the same target. IMO, the powerful scaling is sort of the point of these spells; they are weak but reliable at low spell levels and surprisingly potent at high levels. You can't fire more than 5 missiles with this spell, which would deal 57.5 average damage, split between two targets. This is noticeably less than the average 49 (save for 24) damage per target of the 9th level AoE spell weird, which can target more than two targets, to say nothing of more powerful ones like meteor swarm (which does a whopping 20d6 damage even on a failed save.)

This produces a total damage of 3d4+4 = 7.5+4 = 11.5, very slightly above average for an "auto-hit" spell but spread out between two targets so it isn't that powerful (it's always better to concentrate fire.) When coupled with the "shield or shielding brooch" limitation, I think that's enough to justify being slightly better damage than magic missile on top of having the barrier-cracking utility.
Yes, I noticed the same thing about magic missile's damage. Thanks for walking through it and offering a solution. I think your fix is a strong contender!

My reluctance is that what you're describing sounds similar to chaos bolt, which I'd been trying to veer from – just as I was trying to avoid "magic missile, but MORE" (e.g. that's one of the reasons why I injected new utility for piercing force barriers) – and I think maintaining the original flavor of the bolt exploding (as opposed to ricocheting or leaping to one additional target) is important.
 


Ancalagon

Dusty Dragon
a "partial" idea for the barrier piercing:

What if, as a reaction, someone could go through the hole created? What if each missile punches a hole? What if the hole closes after one person goes through?
 

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