I'm running Out of the Abyss for 5 players. They are in the Battle for Blingdenstone. I have made a fight before the boss battle where they face 2 earth elementals. Rather than a good old slug fest, I thought of using them to cause a cave-in. The earthies are being controlled by a malevolent spirit/force known as Ogrémoch's Bane, allowing them the intelligence of such a move. The strategy is to ideally kill them all (highly unlikely) or slow them down enough for the boss to get reinforced.
Here's where I ran into trouble. I want to make it reasonable for the earthies to cause a cave-in. They do double damage to objects and structures. The DMG states (chapter 8, Objects) that stone has an AC of 17, well within a 50% chance of hitting. A resilient object has 5d10 hp. What amount of damage constitutes a cave-in? or would you advise a number of hits?
A standard earth elemental gets a +8 to hit with its attacks and does an average of 14 bludgeoning damage per hit (double that for objects and structures). If you're looking at your cave walls having ~28 hit points, then the two earth elementals could easily deal that damage in one round if they both hit at least once. It is very reasonable for them to cause a cave in, although you might need them to do damage on a couple sections of wall to bring the everything down. You can roll if you want, but I'd just assume that they'll be successful after 2-3 rounds (unless the characters can do enough to stop both of the elementals from damaging the save).
If this could potentially be a TPK situation, then I would stay with straight dice rolls to see how successful they actually are. Not fair to automatically let things succeed if the results in the characters dying.
Xalthu- Support beams hadn't occurred to me. I've always thought that underdark tunnels were either burrowed by a monster or carved out by a sentient creature.
Javier_Phenergan- those numbers make sense. I definitely don't want to TPK! I'm using a delay tactic to give the PCs a different encounter besides combat. In my mind, stopping or delaying the PCs is tantamount to the bad guy winning. If the bad guy's army succeeds in destroying most of Blingdenstone, its leadership, and people, then the PCs have lost.
Support beams hadn't occurred to me. I've always thought that underdark tunnels were either burrowed by a monster or carved out by a sentient creature.
I was envisioning more of a natural tunnel or cavern as well, but Xalthu's suggestion could be easily converted to stone columns versus support beams. If you want to create a scene where the characters have more of a chance to prevent the earth elementals from causing the cave-in, then you can say there are X-amount of columns that need to be destroyed before the ceiling collapses. Spread them out a bit, so the elemental must move between columns before they can try to strike and destroy them. A perceptive PC might pick-up on the elementals' strategy and can try to impose themselves in front of a column to help defend it.
Those numbers make sense. I definitely don't want to TPK! I'm using a delay tactic to give the PCs a different encounter besides combat. In my mind, stopping or delaying the PCs is tantamount to the bad guy winning. If the bad guy's army succeeds in destroying most of Blingdenstone, its leadership, and people, then the PCs have lost.
And then adjust the above section of this post to fit how best it works with your overall plan. If you are in favor of the earth elementals succeeding in their attempt to collapse the tunnel, then it should be fairly straightforward for them to do so. They are literally in their element for this encounter... If stalling the PCs makes the next phase of the adventure more intense and exciting, then I wouldn't worry too much about the elementals being able to succeed. If the collapsing tunnel dooms Blingdenstone (and allows bad guy to win), then I'd ensure that PCs have a legitimate chance in defeating the earth elementals; such as spreading out columns needing to be smashed.
Yeah, I think I have a good scenario now. The PCs are making their way towards the boss. The tunnel becomes very smooth and an acidic smell is strong in the air. The tunnel is a uniform 10' high and across, the result of oozes eating away at the stone. Support columns are spaced every 15' along and it is evident that their integrity is compromised due to the acid damage.
Up from the floor and out of the walls spring 2 earth elementals, before and behind the PCs. Rather than attack, however, each elemental knocks out the supports closest to them. Each elemental moves away from the party, knocking out columns as they pass. A cave-in is certain if the elementals each knock down 6 columns. It's up to the PCs to stop them and prevent being closed off.
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Hey, thanks for taking a look at my question!
I'm running Out of the Abyss for 5 players. They are in the Battle for Blingdenstone. I have made a fight before the boss battle where they face 2 earth elementals. Rather than a good old slug fest, I thought of using them to cause a cave-in. The earthies are being controlled by a malevolent spirit/force known as Ogrémoch's Bane, allowing them the intelligence of such a move. The strategy is to ideally kill them all (highly unlikely) or slow them down enough for the boss to get reinforced.
Here's where I ran into trouble. I want to make it reasonable for the earthies to cause a cave-in. They do double damage to objects and structures. The DMG states (chapter 8, Objects) that stone has an AC of 17, well within a 50% chance of hitting. A resilient object has 5d10 hp. What amount of damage constitutes a cave-in? or would you advise a number of hits?
A standard earth elemental gets a +8 to hit with its attacks and does an average of 14 bludgeoning damage per hit (double that for objects and structures). If you're looking at your cave walls having ~28 hit points, then the two earth elementals could easily deal that damage in one round if they both hit at least once. It is very reasonable for them to cause a cave in, although you might need them to do damage on a couple sections of wall to bring the everything down. You can roll if you want, but I'd just assume that they'll be successful after 2-3 rounds (unless the characters can do enough to stop both of the elementals from damaging the save).
If this could potentially be a TPK situation, then I would stay with straight dice rolls to see how successful they actually are. Not fair to automatically let things succeed if the results in the characters dying.
Most of the time, tunnels will have beams shoring up the structure. The elemental could attack those beams.
Solid advice!
Xalthu- Support beams hadn't occurred to me. I've always thought that underdark tunnels were either burrowed by a monster or carved out by a sentient creature.
Javier_Phenergan- those numbers make sense. I definitely don't want to TPK! I'm using a delay tactic to give the PCs a different encounter besides combat. In my mind, stopping or delaying the PCs is tantamount to the bad guy winning. If the bad guy's army succeeds in destroying most of Blingdenstone, its leadership, and people, then the PCs have lost.
I was envisioning more of a natural tunnel or cavern as well, but Xalthu's suggestion could be easily converted to stone columns versus support beams. If you want to create a scene where the characters have more of a chance to prevent the earth elementals from causing the cave-in, then you can say there are X-amount of columns that need to be destroyed before the ceiling collapses. Spread them out a bit, so the elemental must move between columns before they can try to strike and destroy them. A perceptive PC might pick-up on the elementals' strategy and can try to impose themselves in front of a column to help defend it.
And then adjust the above section of this post to fit how best it works with your overall plan. If you are in favor of the earth elementals succeeding in their attempt to collapse the tunnel, then it should be fairly straightforward for them to do so. They are literally in their element for this encounter... If stalling the PCs makes the next phase of the adventure more intense and exciting, then I wouldn't worry too much about the elementals being able to succeed. If the collapsing tunnel dooms Blingdenstone (and allows bad guy to win), then I'd ensure that PCs have a legitimate chance in defeating the earth elementals; such as spreading out columns needing to be smashed.
Yeah, I think I have a good scenario now. The PCs are making their way towards the boss. The tunnel becomes very smooth and an acidic smell is strong in the air. The tunnel is a uniform 10' high and across, the result of oozes eating away at the stone. Support columns are spaced every 15' along and it is evident that their integrity is compromised due to the acid damage.
Up from the floor and out of the walls spring 2 earth elementals, before and behind the PCs. Rather than attack, however, each elemental knocks out the supports closest to them. Each elemental moves away from the party, knocking out columns as they pass. A cave-in is certain if the elementals each knock down 6 columns. It's up to the PCs to stop them and prevent being closed off.