D&D 5E Letting the enemy have even a single attack is the result of a strategic failure.

[Eltab]

The straw that broke the camel's back was when we used our Lyre of Building to excavate and drain the entire Water Temple out the side of a mountain.

Now I HAVE to get my PotA group to return to the Earth Temple and finish ransacking it. They've gotta have some earth-moving equipment / magic item in there !

 

[Sword of Spirit]

The problem here is that it requires you to see your target more than 100 feet away and recognize it as something you want to kill. This makes long-distance engagement much more difficult than it might otherwise be. I couldn't find rules anywhere for encounter distance by terrain type.

Apparently there is a 5e DMs screen that does include a table for that. I wish they put it in a product I could use though (the screen isn't going to worth for me--wrong information on it). I never got a response from the designers about whether we might see that table in another product.