D&D 5E Questions!!!

[maritimo80]

) A caster in READY action moves the moonbean spell to the top of the creature in the middle of its turn as a trigger, does this creature save the spell this turn?
2) A creature with 40ft of movement on difficult terrain with plant growth magic, how much movement?
3) A character with 30ft of movement crawling on difficult terrain, moves how much per turn (without Dash)?

 

[jaelis]

) A caster in READY action moves the moonbean spell to the top of the creature in the middle of its turn as a trigger, does this creature save the spell this turn?

So the caster readies an action to move moonbeam? Moonbeam deals damage when a creature enters the spell's area, or when the creature starts its turn in the area. Here the creature did not enter the area (moving the area onto the creature doesn't count, per Sage Advice) nor did it start its turn there. So no, the creature would not be affected.

2) A creature with 40ft of movement on difficult terrain with plant growth magic, how much movement?

I'd say it can move 10 feet; each foot of travel costs 4 feet of movement, per the spell. I don't think it being difficult terrain matters, though I guess it could be debated. (The difficult terrain rule says both movement costs are doubled and that each foot of travel costs 2 feet, so I guess it depends how you want to interpret that.)

3) A character with 30ft of movement crawling on difficult terrain, moves how much per turn (without Dash)?

The rules are clear, crawling through difficult terrain costs 3 feet of movement per foot traveled.

 

[Ovinomancer]

1) the spell only allows you to move it on your turn, so you cannot ready to move it outside of your turn. However, if you rule this is okay, the spell clearly states damage is upon entering the moonbeam or starting your turn there. I'd say having it move over you counts as 'entering'.

2) difficult terrain is usually provided as how much additional movement is needed. So, "normal" difficult terrain is usually presented as needing 1 more foot of movement than normal to move 1 foot, or you pay 2 feet of movement to move 1 foot. Crawling is the same, it costs one extra foot of movement to move 1 foot. Read this way, it's easy to combine difficult terrain penalties. For 2) plant growth is 4 for 1, or it costs 3 extra feet of movement for each 1 foot moved. Added to a 2 for 1 difficult terrain, that means it takes 5 feet of movement (3 extra from plant growth plus 1 extra from difficult terrain plus the base 1 foot) for each foot of movement. So, for 40 feet of movement, you can go 8 feet. Round as you like, but down is normal.

3) like the above, difficult terrain adds 1 more foot of movement needed and crawling does the same, so it's 3 feet of movement for every 1 foot (+1 difficult terrain, +1 crawling, 1 base). So, for 30 feet of movement, you can go 10 ft.

 

[jaelis]

I'd say having it move over you counts as 'entering'.

Just to reiterate, Sage Advice specifically addresses this issue:

Does moonbeam deal damage when you cast it? What about when its effect moves onto a creature?

The answer to both questions is no. Here’s some elaboration on that answer.

Some spells and other game features create an area of effect that does something when a creature enters that area for the first time on a turn or when a creature starts its turn in that area. The turn you cast such a spell, you’re primarily setting up hurt for your foes on later turns. Moonbeam, for example, creates a beam of light that can damage a creature who enters the beam or who starts its turn in the beam.

Here are some spells with the same timing as moonbeam for their areas of effect:
blade barrier
cloudkill
cloud of daggers
Evard’s black tentacles
forbiddance
moonbeam
sleet storm
spirit guardians

Reading the description of any of those spells, you might wonder whether a creature is considered to be entering the spell’s area of effect if the area is created on the creature’s space. And if the area of effect can be moved—as the beam of moonbeam can—does moving it into a creature’s space count as the creature entering the area? Our design intent for such spells is this: a creature enters the area of effect when the creature passes into it. Creating the area of effect on the creature or moving it onto the creature doesn’t count. If the creature is still in the area at the start of its turn, it is subjected to the area’s effect.

Entering such an area of effect needn’t be voluntary, unless a spell says otherwise. You can, therefore, hurl a creature into the area with a spell like thunderwave. We consider that clever play, not an imbalance, so hurl away! Keep in mind, however, that a creature is subjected to such an area of effect only the first time it enters the area on a turn. You can’t move a creature in and out of it to damage it over and over again on the same turn.

In summary, a spell like moonbeam affects a creature when the creature passes into the spell’s area of effect and when the creature starts its turn there. You’re essentially creating a hazard on the battlefield.

Obviously, you're free to ignore that if you like, but it does clearly express the design intent.

 

[Ovinomancer]

Just to reiterate, Sage Advice specifically addresses this issue:

Obviously, you're free to ignore that if you like, but it does clearly express the design intent.

Sure, but you can't ready to move it, either, so we're already in 'not as designed space.' If you allow the former, then ruling it's always moot because it can't hurt seems specious. I'm fine with a 'I move it right in front of it when it's committed to entering that space' kind of thing, because if I'm going to rule you can move it with a ready action, I'm also going to make that choice meaningful.

 

[Jester David]

While moonbeam says you can move it as an action on your turn, I don't see why the specific of using the Ready action would be overruled.
However, the damage of the spell only kicks on when a creature enters or starts in the area. Even if you interrupt the movement, the creature can choose to just walk around.

Plant growth says each foot costs 4 feet of movement. Difficult terrain adds 1 foot. So 5 feet per foot. 40 feet movement gets you 8 feet.

The rules for being prone explicitly say crawling over difficult terrain is 3:1.

 

[Rya.Reisender]

I'd say "on your turn" indicates you can't do that as reaction. Abilities you can trigger as reactions usually say "once per turn" instead. Compare to for example sneak attack. Ready action allows you to use your action on someone else's turn, but it doesn't override spell restrictions.

 

[jaelis]

I think you could expect to see a fair bit of table variation about whether you can move the effect as a readied action. Depends if you think the ready action rule or the spell description has priority here. As a rules lawyer I'd probably lean towards saying the spell is more specific. But at the table I'd probably let it work.

 

[Jester David]

I'd say "on your turn" indicates you can't do that as reaction. Abilities you can trigger as reactions usually say "once per turn" instead. Compare to for example sneak attack. Ready action allows you to use your action on someone else's turn, but it doesn't override spell restrictions.

Sneak attack is specific on that, as it can apply to things like opportunity attacks.

But it really comes down to what you consider the specific and what the general. Is the base rule the Ready action and moonbeam is the more specific exception? Or is moonbeam's text general and Readying the exception?

 

[Ovinomancer]

Sneak attack is specific on that, as it can apply to things like opportunity attacks.

But it really comes down to what you consider the specific and what the general. Is the base rule the Ready action and moonbeam is the more specific exception? Or is moonbeam's text general and Readying the exception?

Pretty clearly Ready is the general, as it's presented in the general rules section, while Moonbeam is the specific, as it's text only applies to Moonbeam.