D&D 5E Cost/Benefit Analysis of True Strike

[KarinsDad]

NUANCE: The spell description for TS says "You point your finger at a target...", perhaps implying that you can't use TS on a target you can't see or pinpoint somehow. However, the most common source of disadvantage on attacks is not being able to see the target. Since the expected damage advantage of TS+Attack over Attack+Attack is small, if your DM rules that you can't TS someone you can't see, then I think the cost of learning this cantrip is not worth the benefit if you intend to use it mainly with free attacks.

Why would a DM do that? I think you are reading too much into those words. A PC can point to a square or an invisible target as long as the PC is not physically or mentally prevented from doing so. It doesn't matter if a PC cannot see an NPC, he can still point at the square where he thinks the NPC is located and that is sufficient for the targeting rules.

It's pretty clear from the rules that one can target an invisible foe, so it's pretty clear that one can point their finger at an invisible foe. I think that the spell would have to explicitly state that it cannot target an invisible foe for it to have that property.

 

[guachi]

I suppose if you, say, had no ranged weapon that casting True Strike would be useful to do while you moved to melee range.

Thank you for the math explanation and formatting. It looks better than when I try to explain things.

 

[jrowland]

Other times when true strike is handy:

Creatures are out of range for other spells/attacks - cast true strike to set up for next round when they are in range
Any round you have no good targets (you have dis, people in way, etc) but expect that to change
When playing darts in the pub (ie roleplaying)
Hail Mary shots - enemy is fleeing and 1 round won't have target out of range, but you are at dis and want to make sure it hits.

 

[Stalker0]

Other times when true strike is handy:

Creatures are out of range for other spells/attacks - cast true strike to set up for next round when they are in range
Any round you have no good targets (you have dis, people in way, etc) but expect that to change
When playing darts in the pub (ie roleplaying)
Hail Mary shots - enemy is fleeing and 1 round won't have target out of range, but you are at dis and want to make sure it hits.

One other...you have a round to buff before rushing into a room...the old "kick down the door and charge" scenario.

 

[fuindordm]

Valid point above about the relative benefits of casting TS vs casting another cantrip.
And yes, it is also generally better to go nova and cast one's most powerful spells as often as possible.
The scenarios above are only indicative, as a real combat has many more variables and possible choices.

Let's run the numbers on a slightly more concrete situation:

The party is fighting a gnoll captain plus several mooks, and the mooks are holding the line thanks to the captain's leadership. The wizard wants to hurt the captain, but doesn't want to go nova since it's just the first encounter of the sortie. So the option of spending two spell slots is off the table due to PC preference.

Let's compare these 4 scenarios:
S1: TS followed by Acid Arrow (average 15 damage)
S2: Fire bolt (average 5 damage, not 5.5, to make the math a little easier), followed by Acid Arrow.
S3: as S1, but with disadvantage (for example, because the captain is invisible)
S4: as S2, but with disadvantage
Let's say the wizard needs a 11 to hit.
Define ED = expected damage

S1: ED = P(hit)*15 = 15*[1-(11-1)^2/400] = 15*300/400 = 11.25
S2: ED = 0.5*5 + 0.5*15 = 10
S3: ED = 0.5*15 = 7.5
S4: ED = [(21-11)^2/400]*5 + [(21-11)^2/400]*15 = 0.25*20 = 5
So in both cases casting TS is better than casting a cantrip for damage to set up your high-level spell, under the assumption that you only want to spend one high-level slot.

What if captain is easier to hit? Let's make the roll to hit 6 (75% chance) Then:

S1: ED = 15*[1-(6-1)^2/400] = 15*375/400 = 14
S2: ED = 0.75*5 + 0.75*15 = 15
S3: ED = 0.75*15 = 11.25
S4: ED = [(21-6)^2/400]*20 = 11.25

What if the captain is very hard to hit, for example because he has cover? (target roll is 16)

S1: ED = 15*[1-(16-1)^2/400] = 15*175/400 = 6.56
S2: ED = 0.25*5 + 0.25*15 = 5
S3: ED = 0.25*15 = 3.75
S4: ED = [(21-16)^2/400]*20 = 1.25

So the trend is pretty clear: if you want to conserve spell slots, and have time to set up an attack, TS compares pretty favorably to leading with a damaging cantrip. Yes, you need to balance that against the need to finish the combat earlier rather than later to mitigate damage to the party, and so on.

 

[Pickles JG]

TS is also useful for an Arcane Trickster shooting at something he cannot otherwise sneak attack as it provides advantage. 1d6+n twice << many d6+n with greater accuracy, for values of "many" that are large.

Fighting a "Solo" monster is likely to to last for a few rounds & there is no time value to damage so that is a good time to use TS too. There is time value to other effects debuffs etc so there may still be an opportunity cost.

I think it's OK
as your pre-combat buff,
to set up a huge daily spell when you know the fight is going to last - vs a dragon/solo,
for rogues &
for when you have nothing better to do.

 

[Sacrosanct]

TS is also useful for an Arcane Trickster shooting at something he cannot otherwise sneak attack as it provides advantage. 1d6+n twice << many d6+n with greater accuracy, for values of "many" that are large.
.

Or really, any rogue with a magic initiate feat as well.

 

[BryonD]

The only really good use I've thought of is an Arcane Trickster who may frequently be hiding and waiting to attack, thus not giving up the opportunity.

Even then I'm not sure.

 

[Ilbranteloth]

I think you'd be better off casting Faerie Fire first (to benefit all of your allies), then using Chill Touch, Eldritch Blast, Fire Bolt, and/or Ray of Frost from there, since these are all ranged attack spells and you'd have advantage to hit with them. You'd potentially ruin any Hiding or invisible targets as well.

I'd love to see the math using Faerie Fire instead of True Strike.

Ilbranteloth

 

[Ilbranteloth]

Doh! Somebody pointed out that Faerie Fire isn't a wizard spell. I was thinking of my daughter's druid. I'd still love to see the math though.

Ilbranteloth