BeefGood
2017-08-24, 09:46 PM
Here are homebrew snow avalanche rules. They've been tried once and it went okay. The (9th level) characters cast Wall of Stone to ward off the avalanche, which I thought was a fine solution. However, I didn't want my time planning the avalanche to go to waste so I ruled that they got hit with a lesser avalanche anyway. I had bad guys pounce on them immediately after the avalanche, and the characters cast Wall of Fire to keep them away until they had dug out the buried party members.
I'm concerned that there are too many rules to remember. Especially, keeping track of the party members who have been moved downslope and buried, and keeping track of the un-buried party members' attempts to find them, is challenging--more so if you add a combat to it, as I did.
Finally, an important decision is whether you really want your characters to die buried in snow rather than, for example, in a glorious battle with a dragon. The possibility of suffocation has to be handled carefully to get the result you are comfortable with. I did not want an avalanche to be an auto-kill so I allowed 10 minutes of air to creatures buried in snow, set the main saving throw DC to 15 rather than 20, and gave buried characters the ability to clear space to cast spells or even dig themselves out. This last ability is not in accord with verisimilitude, according to Wikipedia's "Avalanche Rescue" article which contains some pretty grim reading.
Others' opinions are welcome.
Preliminaries
Detect
* A DC 10 Intelligence(Nature) check detects that conditions are conducive to an avalanche.
* An unnatural avalanche trigger (e.g. evil creatures using levers to tip chunks of snow down the slope) can be detected in a way appropriate to the trigger (e.g. a Wisdom(Perception) check opposed by the evil creatures’ Dexterity(Stealth) check).
Disable
* The only way to disable a naturally-triggered avalanche is to trigger it. (See the discussion of Spells under Triggers below for some possible exceptions.)
* An avalanche that is triggered by unnatural means can be disabled by disabling the trigger (e.g. killing or chasing away the evil creatures.)
Avoid
* Characters may be able to avoid an avalanche-prone area by taking a different route.
o Add 1d3 days to journey
* Or there may be no passable different route.
Avalanche Trigger and Relevant Spells
Triggers
* DM fiat
* Unnatural mechanical trigger (e.g. levers).
* Spells. At the DM’s discretion, a variety of spells could trigger an avalanche. Evil creatures might use a spell to trigger the avalanche on unwary travelers, or cautious travelers might use a spell to trigger the avalanche defensively, to pass by in safety afterward. The spell’s range relative to the distance to the trigger point, which is left to the DM’s discretion, is an important consideration. Thoughts on some spells are below.
o Thunderwave (1st Level): An excellent choice for creatures at the trigger point to trigger the avalanche, but not useful otherwise because of the extreme short range (15’). Note that the “thunderous boom audible out to 300 feet” is presumed to not be sufficient to trigger an avalanche due to verisimilitude (Wikipedia says that sound is much too weak to start an avalanche) but the DM is certainly free to rule otherwise.
o Shatter (2nd Level): As for Thunderwave, a good choice for creatures near the trigger point, but the limited range (60’) makes it not useful for creatures at the bottom of the slope.
o Gust of Wind (2nd Level): A blast of wind that can push a creature 15 feet seems like a good avalanche-starter, from relatively close range (60’).
o Fireball (3rd Level), Lightning Bolt (3rd Level): Despite the language in these spells’ descriptions, I don’t think of either as having much explosive or penetrating power. Perhaps Lightning Bolt before Fireball.
o Sleet Storm (3rd Level), Ice Storm (4th Level): Ice Storm’s 300-foot range makes it an excellent choice for defensive triggering of the avalanche. Sleet Storm’s 150-foot range might or might not be adequate. The DM could either rule that these spells “tamp down” the unstable material, eliminating the avalanche danger, or that the added weight of the precipitation triggers the avalanche.
o Bigby’s Hand (5th Level): The 120-foot range is not ideal for defensive triggering. Other than that, this spell seems like a good avalanche-starter.
Effects of Snow Avalanche
Unless distracted, creatures notice the avalanche one round before it strikes.
Creatures in the path of the avalanche make a DC 15 Strength or Dexterity saving throw. On a success, the creature takes half damage and is knocked prone. On a failure, the creature takes full damage and is knocked prone. Creatures failing the saving throw by 5 or more take full damage, are moved downslope the distance indicated, and buried within the depth range indicated.
Avalanche Category
Width
Damage (hp)
Moved (hex or square)
Buried (depth)
Tier 1
30'
14 (4d6)
1d2
0' to 5'
Tier 2
60'
35 (10d6)
1d4
5' to 10'
Tier 3
90'
63 (18d6)
2d4
10' to 15'
Tier 4
120'
84 (24d6)
3d4
15' to 20'
Rules for Creatures Buried in Snow
* Creatures buried in snow have 10 minutes of air. Then suffocation rules apply.
o Hold breath for (1 + Constitution modifier) minutes (minimum 30 seconds)
o Then survive for (Constitution modifier) rounds
o Then drop to 0 hit points and roll a d20 each round:
--9 or below is a fail.
--Natural 1 counts as two fails.
--Natural 20 subtracts a fail.
--Dead on three fails.
* In one minute, a buried creature can clear space to speak the verbal component of spells.
* In two minutes, a buried creature can clear space to speak the verbal components of spells, perform the somatic components of spells, and access the material components of spells.
* A buried creature can dig itself out at half the unaided digging rate (see Digging Rules.) For example, a creature having strength 15, buried 0' to 5' deep, can dig itself out in 3 minutes. The same creature buried 5’ to 10’ deep would need 6 minutes to dig out; buried 10' to 15' deep, 9 minutes. If this creature were buried 15' to 20' deep, 12 minutes would be required to dig out, and suffocation would be a possibility.
Locating a Creature Buried in Snow
Locating a creature buried in snow requires a search of the area near the buried creature, a means of perception, and a corresponding ability check. As an action, in one minute, a creature can search from a 5-foot surface square or hex, to the range determined by its means of perception.
Some suitable means of perception and their ability checks are:
* Keen Sense (smell); Wisdom(Perception) check. A nondirectional means of perception such as smell can detect a buried creature in any direction. To determine the distance, either use the maximum of the distances along the three grid directions, or use a more sophisticated method such as the rules for diagonal motion in the DMG.
* Pole/weapon of sufficient length; Strength(Perception) check
Distance
DC to find
0' to 5'
5
5' to 10'
10
10' to 15'
15
15' to 20'
20
Digging Rules
* A character can clear 50 times his or her Strength score, in pounds, per minute.
* An appropriate tool doubles the rate.
* Helping reduces the time proportionally.
* The unaided time to clear a 5’ cube of snow is shown in the table below. The values in the table are roughly based on 1,000 pounds per 5’ cube of snow.
Strength
Time (minutes)
20
1
15
1.5
10
2
5
4
I'm concerned that there are too many rules to remember. Especially, keeping track of the party members who have been moved downslope and buried, and keeping track of the un-buried party members' attempts to find them, is challenging--more so if you add a combat to it, as I did.
Finally, an important decision is whether you really want your characters to die buried in snow rather than, for example, in a glorious battle with a dragon. The possibility of suffocation has to be handled carefully to get the result you are comfortable with. I did not want an avalanche to be an auto-kill so I allowed 10 minutes of air to creatures buried in snow, set the main saving throw DC to 15 rather than 20, and gave buried characters the ability to clear space to cast spells or even dig themselves out. This last ability is not in accord with verisimilitude, according to Wikipedia's "Avalanche Rescue" article which contains some pretty grim reading.
Others' opinions are welcome.
Preliminaries
Detect
* A DC 10 Intelligence(Nature) check detects that conditions are conducive to an avalanche.
* An unnatural avalanche trigger (e.g. evil creatures using levers to tip chunks of snow down the slope) can be detected in a way appropriate to the trigger (e.g. a Wisdom(Perception) check opposed by the evil creatures’ Dexterity(Stealth) check).
Disable
* The only way to disable a naturally-triggered avalanche is to trigger it. (See the discussion of Spells under Triggers below for some possible exceptions.)
* An avalanche that is triggered by unnatural means can be disabled by disabling the trigger (e.g. killing or chasing away the evil creatures.)
Avoid
* Characters may be able to avoid an avalanche-prone area by taking a different route.
o Add 1d3 days to journey
* Or there may be no passable different route.
Avalanche Trigger and Relevant Spells
Triggers
* DM fiat
* Unnatural mechanical trigger (e.g. levers).
* Spells. At the DM’s discretion, a variety of spells could trigger an avalanche. Evil creatures might use a spell to trigger the avalanche on unwary travelers, or cautious travelers might use a spell to trigger the avalanche defensively, to pass by in safety afterward. The spell’s range relative to the distance to the trigger point, which is left to the DM’s discretion, is an important consideration. Thoughts on some spells are below.
o Thunderwave (1st Level): An excellent choice for creatures at the trigger point to trigger the avalanche, but not useful otherwise because of the extreme short range (15’). Note that the “thunderous boom audible out to 300 feet” is presumed to not be sufficient to trigger an avalanche due to verisimilitude (Wikipedia says that sound is much too weak to start an avalanche) but the DM is certainly free to rule otherwise.
o Shatter (2nd Level): As for Thunderwave, a good choice for creatures near the trigger point, but the limited range (60’) makes it not useful for creatures at the bottom of the slope.
o Gust of Wind (2nd Level): A blast of wind that can push a creature 15 feet seems like a good avalanche-starter, from relatively close range (60’).
o Fireball (3rd Level), Lightning Bolt (3rd Level): Despite the language in these spells’ descriptions, I don’t think of either as having much explosive or penetrating power. Perhaps Lightning Bolt before Fireball.
o Sleet Storm (3rd Level), Ice Storm (4th Level): Ice Storm’s 300-foot range makes it an excellent choice for defensive triggering of the avalanche. Sleet Storm’s 150-foot range might or might not be adequate. The DM could either rule that these spells “tamp down” the unstable material, eliminating the avalanche danger, or that the added weight of the precipitation triggers the avalanche.
o Bigby’s Hand (5th Level): The 120-foot range is not ideal for defensive triggering. Other than that, this spell seems like a good avalanche-starter.
Effects of Snow Avalanche
Unless distracted, creatures notice the avalanche one round before it strikes.
Creatures in the path of the avalanche make a DC 15 Strength or Dexterity saving throw. On a success, the creature takes half damage and is knocked prone. On a failure, the creature takes full damage and is knocked prone. Creatures failing the saving throw by 5 or more take full damage, are moved downslope the distance indicated, and buried within the depth range indicated.
Avalanche Category
Width
Damage (hp)
Moved (hex or square)
Buried (depth)
Tier 1
30'
14 (4d6)
1d2
0' to 5'
Tier 2
60'
35 (10d6)
1d4
5' to 10'
Tier 3
90'
63 (18d6)
2d4
10' to 15'
Tier 4
120'
84 (24d6)
3d4
15' to 20'
Rules for Creatures Buried in Snow
* Creatures buried in snow have 10 minutes of air. Then suffocation rules apply.
o Hold breath for (1 + Constitution modifier) minutes (minimum 30 seconds)
o Then survive for (Constitution modifier) rounds
o Then drop to 0 hit points and roll a d20 each round:
--9 or below is a fail.
--Natural 1 counts as two fails.
--Natural 20 subtracts a fail.
--Dead on three fails.
* In one minute, a buried creature can clear space to speak the verbal component of spells.
* In two minutes, a buried creature can clear space to speak the verbal components of spells, perform the somatic components of spells, and access the material components of spells.
* A buried creature can dig itself out at half the unaided digging rate (see Digging Rules.) For example, a creature having strength 15, buried 0' to 5' deep, can dig itself out in 3 minutes. The same creature buried 5’ to 10’ deep would need 6 minutes to dig out; buried 10' to 15' deep, 9 minutes. If this creature were buried 15' to 20' deep, 12 minutes would be required to dig out, and suffocation would be a possibility.
Locating a Creature Buried in Snow
Locating a creature buried in snow requires a search of the area near the buried creature, a means of perception, and a corresponding ability check. As an action, in one minute, a creature can search from a 5-foot surface square or hex, to the range determined by its means of perception.
Some suitable means of perception and their ability checks are:
* Keen Sense (smell); Wisdom(Perception) check. A nondirectional means of perception such as smell can detect a buried creature in any direction. To determine the distance, either use the maximum of the distances along the three grid directions, or use a more sophisticated method such as the rules for diagonal motion in the DMG.
* Pole/weapon of sufficient length; Strength(Perception) check
Distance
DC to find
0' to 5'
5
5' to 10'
10
10' to 15'
15
15' to 20'
20
Digging Rules
* A character can clear 50 times his or her Strength score, in pounds, per minute.
* An appropriate tool doubles the rate.
* Helping reduces the time proportionally.
* The unaided time to clear a 5’ cube of snow is shown in the table below. The values in the table are roughly based on 1,000 pounds per 5’ cube of snow.
Strength
Time (minutes)
20
1
15
1.5
10
2
5
4