How does casting a "line" spell work on a grid?

[MissJynx]

Hi there, our group recently switched the 5th Ed. and we are still very new at it.
We use a battle grid for our minis to simplify combat.

Last game our bard cast a lightning bolt via a enchanted sword he got, and the group couldn't agree on how to use the "line effect" of the spell, as he was trying to hit two targets on different lines of the grid. I told him I'd let his strike hit this time, but I'd research it for the next game.

So, far as my research in the DMG and PHB goes (and multiple forums), it seems to be left to the DM's discretion.
What would you suggest?
Should the line effect only go in straight, grid lines? (which would restrict the line to the character's square sides, or corners, and would limit it to 8 possible lines)
Or should the line be whatever can be measured in a straight line coming from the caster, as long as it's straight and respects the spell's width ? (which would mean almost infinite possibilities of lines)

Thanks!

[ruy343]

Rather than rely on coming up with a grid pattern to use, you could use a string (or a ruler) that emanates out from the caster that's cut out to be X squares in length (to match the spells range when shot straight along the squares). Any creature that the string (or ruler) would cross is affected.

[dejarnjc]

Hi there, our group recently switched the 5th Ed. and we are still very new at it.
We use a battle grid for our minis to simplify combat.

Last game our bard cast a lightning bolt via a enchanted sword he got, and the group couldn't agree on how to use the "line effect" of the spell, as he was trying to hit two targets on different lines of the grid. I told him I'd let his strike hit this time, but I'd research it for the next game.

So, far as my research in the DMG and PHB goes (and multiple forums), it seems to be left to the DM's discretion.
What would you suggest?
Should the line effect only go in straight, grid lines? (which would restrict the line to the character's square sides, or corners, and would limit it to 8 possible lines)
Or should the line be whatever can be measured in a straight line coming from the caster, as long as it's straight and respects the spell's width ? (which would mean almost infinite possibilities of lines)

Thanks!


I just eyeball a straight line from the PC to the point and judge what looks like it should be included, i.e. the straight line can go in any of 360 directions. If it looks tricky, I use a piece of string. If some creatures seem iffy as to whether they'd be in the AoE I usually err in the player's benefit because line spells are tricky.

[tieren]

We use a straight line, like a pencil, ruler, or pipe cleaner and have it start from any point in the caster's space.

For cones, spheres and cubes we have different paper cut outs to overlay to see what we can impact.

[RaynorReynolds]

I think what the poster is trying to get at is that drawing a line that doesnt line up with a row or column only partially goes through some squares. Do characters in those squares take full damage? Do they get advantage on their save?

[BW022]

I think what the poster is trying to get at is that drawing a line that doesnt line up with a row or column only partially goes through some squares. Do characters in those squares take full damage? Do they get advantage on their save?

Lightning bolt is a line 100' long and 5' wide.

Two three ways...

Simple. Draw a line (ruler or book edge) from the center of the source square to the center of that target square -- and beyond. If any square touches any part of the line, anyone in it takes 100% effect. Any square not touched by the line takes no effect. You can often just eye-ball it with string or a straight edge without drawing the line. However, this doesn't work well for a near or exact 45 degree angle.

Accurate Enough. Draw two lines (ruler or book edge) from the outside points of the source square to the outside edges of the target square -- and beyond. Go through each square between the two lines and shade in any which is 50% or more within the squares. Anyone within the shaded squares takes 100% effect. Anyone in any other square (even if it partially touches a line) is unaffected. This is fairly accurate as technically the line is 7' wide.

Perfectly Accurate. Trace out a paper template -- 1" wide and 20" long. Move all the figs. Put the template where the caster wishes. Put all the figs back. Any which is touching the template gets 100% effect.

I would never bother with advantage for being in partial squares. Too time consuming and it encourages casters to take way too much time trying to aim the spell at the angle to get everyone fully.

As long as you are consistent (enemy spells work the same way), you are typically fine.

[Kane0]

Thin ruler or tape measure, they're usually about 1" wide so fit just right. If you don't cover the target they arent affected

[Socratov]

Lightning bolt is a line 100' long and 5' wide.

Two three ways...

Simple. Draw a line (ruler or book edge) from the center of the source square to the center of that target square -- and beyond. If any square touches any part of the line, anyone in it takes 100% effect. Any square not touched by the line takes no effect. You can often just eye-ball it with string or a straight edge without drawing the line. However, this doesn't work well for a near or exact 45 degree angle.

Accurate Enough. Draw two lines (ruler or book edge) from the outside points of the source square to the outside edges of the target square -- and beyond. Go through each square between the two lines and shade in any which is 50% or more within the squares. Anyone within the shaded squares takes 100% effect. Anyone in any other square (even if it partially touches a line) is unaffected. This is fairly accurate as technically the line is 7' wide.

Perfectly Accurate. Trace out a paper template -- 1" wide and 20" long. Move all the figs. Put the template where the caster wishes. Put all the figs back. Any which is touching the template gets 100% effect.

I would never bother with advantage for being in partial squares. Too time consuming and it encourages casters to take way too much time trying to aim the spell at the angle to get everyone fully.

As long as you are consistent (enemy spells work the same way), you are typically fine.
I find myself agreeing with you. draw a template, touch it, you get hurt. Other option, draw a line, it passes through your square? You get hurt. Simple and fun (missing people with a AOE spell is not fun).

[Grod_The_Giant]

I would never bother with advantage for being in partial squares. Too time consuming and it encourages casters to take way too much time trying to aim the spell at the angle to get everyone fully.
Pretty much this. My usual approach is a quick eyeball and "eh, looks like you can hit these guys, yeah."

[Flashy]

Pretty much this. My usual approach is a quick eyeball and "eh, looks like you can hit these guys, yeah."

Especially since it's the exact same damage as fireball in a shape that's harder to aim. If it looks like you can hit the people then fine, you can hit the people.

[Socratov]

Especially since it's the exact same damage as fireball in a shape that's harder to aim. If it looks like you can hit the people then fine, you can hit the people.

Well, the damage type is more fortunate so that's there to compensate for the AOE shape. That said, let it hit. It will hardly break the game into bits.

[Toofey]

This is DM's choice (clearly) I have line attack hit anyone in any square the line goes through, but that's because I'm a big fan of FTL.

[Drackolus]

Yeah, I tend to be the "yeah whatever" kind of dm. I also tend to be just as easy with the monsters, so it evens out and it's the kind of game my players like. If your players want challenge and absolute predictable consistency (i.e. a more 3e kind of crowd), then I think cutouts and >50% of the square (so you can't go down an edge and get effectively all of 2 rows, but you could angle it to crossover in the middle or something.) It will multiply the amount of time the spellcast takes by an order of magnitude, so unless you have the kind of players who are willing to wait, it just isn't worth exacerbating the problem of spellcasters taking longer on their turns. Plus, being forgiving helps prevent issues where the caster only wants to cast that spell if it can hit so many targets, spends 10 minutes figuring out the area only to find out they may need another spell. Don't make the complicated thing more complicated.

[Daishain]

I have a one inch wide ruler I use for this purpose, the player gets to lay it down any way they please so long as the middle of the base is touching their square somehow. Any square on the map that gets significantly covered (IE more than an eyeballed 20%), is affected along with creatures residing on said square.

[ClearlyTough69]

Other option, draw a line, it passes through your square? You get hurt.

This is the best solution. Provided you are using a grid where each square represents five feet, mathematically it has the same effect as using a one inch wide template, without the fuss of estimating what proportion of a square is covered by the template.

[Joe the Rat]

I'd go with one of the "natural" solutions above. Particularly about the partial hits - 5' line is a pretty crappy thing to aim.

But if you really need to keep it to whole grid squares...

True Diagonal: zig-zag. The line goes through the diagonal squares, plus the connecting squares to the left OR right (Caster's Choice). NOT BOTH. Here's an example (origin in Bold, overlaps in Red)





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The other half of the Compass Rose: Pick a stepping pattern (every 2nd, 3rd, 4th, etc. squares.) When you shift, have an overlap on the shift (similar to the diagonal above). Here's an every 2nd shift.




X
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The real wrinkle on these is ranges. Roughly, your bolt should cover the same number of squares (a 100' lightning bolt is 20 5' squares long). Count each overlap square as 1/2.