What Lovecraftian Monter(s) would you like to see in a future game?

[The Rock Worm]

I've seen videos of players who killed an Infected using a box and hitting it repeatedly. Tough Skin/Regeneration would help versus situations like this.

Ok that makes sense I guess.

As for added scare, What if the Deep Ones were sonar proof? You pick up, let's say, a Dwarf Lantern Shark on sonar when all of a sudden a Deep One lunges for you! Let's say Anglers are completely invisible to sonar, but while the Dunkleosteus ones are as well they can choose to appear as a tiny fish to fool you!

...that could work...but the player needs to learn the connection "sonar bleep = enemy" first, before you can play evil tricks on him, I think... it's like the experiment with Pavlovs dog : First, teach the player to expect danger after the bleep. Then, the bleep alone becomes a tool to scare and confuse him, even when nothing is happening.

The idea that you can pick up fishes with it too is really good, it makes for uncertainty. I also like the idea that you can get an estimate of the size of the object you're picking up. So your sonar shows you fish, maybe one or two human sized enemies and then, just when you've learned what the dot sizes on the screen represent in the real world, all of a sudden you see this really huge dot...like ten times the size of the others. And it's moving FAST!

As for the player himself, we would need something to act as the scuba mask and air tanks. Now finding the wreck of a NAVY Sub, or an unfortunate diver in a Deep One City in the wall of a Deep Sea Trench, could offer 'batteries' for your light and extra air tanks.

Oh yes, Deep One City is a must-have. But...how do you change a battery underwater?

I agree that we should have "sonar bleep = enemy" before introducing the trick. Since large squids (such as the ones in the Sea of Cortez) have been known to attack people, why not have a deep sea squid go after you? Nothing too big, but enough to be a concern.

Good question, how does one change a battery underwater? For that matter, getting a new air tank. Aside from having a pocket of air to use (say the wreck of that NAVY Sub), you might have a special 'water proof' battery that stays on good and is easy to change, but takes time (which means you can't change it if on the 'run'). New Air Tanks, you have to have air to change them... or start changing into a Deep One.