D&D 5E How broken is tunneling speed?

[NaturalZero]

Over the years there's been plenty of discussion about the effect of fly speed on games. Some DMs are fine with 1st level PCs having it right out of the gate (aarokocra, tiefling variant, etc) while others prefer it be limited in order to shut down encounter-circumventing tactics. In 4e, flight was very limited because the designers believed that easy access to flight negated to many common encounter tropes.

I'm building homebrew classes and was looking at tunnel speed (Edit: i meant burrow speed). It seems super duper extra OP, especially when combo'ed with something like cunning action disengage. Has anyone experienced PCs with tunnel speed at their table? Was it broken? What do you feel would be a good level to start allowing PCs access to tunnel speed?

EDIT: Burrowing speed. I mean burrowing without making a tunnel.

 

[MarkB]

Would you even need Disengage? If you dig straight down, then by the time you leave someone's reach you're already underground. Would they even get to make an attack?

 

[Horwath]

Would you even need Disengage? If you dig straight down, then by the time you leave someone's reach you're already underground. Would they even get to make an attack?

AoO happens when you TRY to leave the reach. It still hits you when you are in the next square.

 

[MarkB]

AoO happens when you TRY to leave the reach. It still hits you when you are in the next square.

Yeah, but if you're not choosing to leave a tunnel behind you (which only some burrowing creatures can do), are you even still visible by the time you try to leave that square?

 

[Steampunkette]

There's a few questions we need answered before we can fully weigh in. I'll throw out a couple and offer an idea that has a presumed answer.

1) How does the character tunnel?
If they tunnel with mole-hands then they need to stop what they're doing, put their weapons away to free up their claws, and start digging. If they just provide an aura of dirt-displacement and "Fly Down" that'd be a wholly different thing.

2) What are the limitations to tunneling?
In 5e, tunneling creatures can move through sand, earth, snow, mud, and ice but they cannot burrow through solid stone. On it's face, this limits your burrowing character's ability to tunnel while in dungeons, cities, or other environments where loose material is more scarce and hard-packed or stone material is much more common. Spending a round to rip up paving stones -before- you can tunnel in a city-street would be interesting.

3) What is the tunnel structure?
5e makes no presumption about how the tunneling happens, as it's a creature to creature trait. Some creatures, like Earth Elementals, just flow through the ground and leave no tunnel. Others, like a Purple Worm, leave tunnels large enough to become Adventure Areas when you have enough purple worms digging through the area to make a mish-mash of intersecting tunnels.

4) How does Difficult Terrain work for tunneling?
Does a thickly rocky medium make tunneling harder, slowing down your tunneler's movement in places without solid stone? Does particularly wet sand or soil make things more complicated? Does a thick clay just make everything a mess and slow someone using a burrow speed down? Or is it "Stone stops you and nothing else matters"? I imagine WotC never felt the need to answer this question as burrowing speeds are much rarer than fly speeds.

So... Assuming a mole-man who can't dig through solid rock and who gets slowed up by various material compositions as difficult terrain who leaves behind a tunnel? No problem at all. His enemies can always follow into the tunnel to try and keep fighting, he has to disarm himself to dig, but it gives him a unique mode of travel to overcome obstacles. Just make sure there's plenty of "We can't go over! We'll have to go... under..." moments.

The further you get from that baseline, though, the harder it's going to be.

Yeah, but if you're not choosing to leave a tunnel behind you (which only some burrowing creatures can do), are you even still visible by the time you try to leave that square?

Just apply a cover bonus. It's not significantly different than an opportunity attack as someone tries to dash around a corner or hide behind a piece of furniture. It's just "Down" instead of lateral.

 

[R_J_K75]

Does anyone really want this guy as their PC?

 

[Voadam]

View attachment 143776
Does anyone really want this guy as their PC?

Absolutely!

 

[NaturalZero]

You know what guys, I typed "tunnel" but I meant "burrow" speed. There's big difference between just moving through the ground and leaving a tunnel.

Yeah, but if you're not choosing to leave a tunnel behind you (which only some burrowing creatures can do), are you even still visible by the time you try to leave that square?

The only way OAs make sense to me in 5e is to treat them just like 3e and 4e. If you're making an attack with a weapon that has a reach of 5 feet, it only functions mechanically if the attack happens before the target leaves the square. This also lines up with the sentinel feat.

1) How does the character tunnel?
If they tunnel with mole-hands then they need to stop what they're doing, put their weapons away to free up their claws, and start digging. If they just provide an aura of dirt-displacement and "Fly Down" that'd be a wholly different thing.

In my hypothetical, I'm reinterpreting the totemist class from 3.5. The bulette and purple worm are both magical beasts that lend conceptual powers, so this would be a character who can just dig at whatever speed they're allowed once they get access to the features. At this point, I'm leaning at leaving out all burrow speed because I imagine disengage being abused and characters being effectively invulnerable when it's not their turn.

2) What are the limitations to tunneling?
In 5e, tunneling creatures can move through sand, earth, snow, mud, and ice but they cannot burrow through solid stone. On it's face, this limits your burrowing character's ability to tunnel while in dungeons, cities, or other environments where loose material is more scarce and hard-packed or stone material is much more common. Spending a round to rip up paving stones -before- you can tunnel in a city-street would be interesting.

Having worked stone block burrowing means it won't be universally OP. What I'm worried about is immunity to damage every round whenever there's dirt though.

4) How does Difficult Terrain work for tunneling?
Does a thickly rocky medium make tunneling harder, slowing down your tunneler's movement in places without solid stone? Does particularly wet sand or soil make things more complicated? Does a thick clay just make everything a mess and slow someone using a burrow speed down? Or is it "Stone stops you and nothing else matters"? I imagine WotC never felt the need to answer this question as burrowing speeds are much rarer than fly speeds.

The basic burrow speed in the MM stops at stone but lets you go through sand, earch, mud, and ice though. You could start making rough terrain for burrow speed but I don't really want to roll in a pile of rules for it just for one feature.

 

[jgsugden]

View attachment 143776
Does anyone really want this guy as their PC?

I would not use him in this type of role playing.

There are some questions about how reach and tunneling/incorporeal work. However, as I read it: When a creature enters total cover adjacent to an enemy, that enemy does not get an OA against the creature entering total cover.

The rules (straight from the PHB in various spots): You can make an opportunity attack when a hostile creature that you can see moves out of your reach. Most creatures have a 5-foot reach and can thus attack targets within 5 feet of them when making a melee attack. A target with total cover can't be targeted directly by an attack.

When an adjacent enemy with a tunneling ability is next to an opponent with a 5' reach, and that enemy tunnels or enters ground otherwise, they are not leaving the reach of the potential attacking opponent. They're still in reach, but they gain total cover. When they leave reach by moving 5 further feet away, that total cover prevents an attack.

Is this overpowered? It is essentially like having a more reliable version of the blink spell. Enemies have to resort to readied actions, which may or may not trigger as you may or may not attack them - and the interpretation of the specificity of readied actions can range between making those readied attacks fairly easy to achieve to nearly impossible. It is strong in combat, and strong from a threat/barrier bypass approach - but it is also something that a 2nd level moon druid (or 4th level any druid) can do as a giant badger in wildshape, although that is not the most fearsome of creatures in combat (but not so bad, either).

I would be a bit hesitant to give it to a PC race, but if the player is not doing it specifically to be uber awesome in combat, I would allow it.

 

[Tales and Chronicles]

Having worked stone block burrowing means it won't be universally OP. What I'm worried about is immunity to damage every round whenever there's dirt though.

One way of doing this would be to imitate the limitations of some flight speed.
You know how some flying creatures must land after a flight, they cant stay in the air?

Do the same for your burrowing speed. You can tunnel at 30 ft speed, but you must exit at the end of your turn or you are shunt to the nearest free space on the surface.

EDIT:
or go the tortles' way: you can move through earth as a bonus action, but when you are underground, you cant do nothing until you as an action.