What traps, terrain, and hazards stand out in your mind?
What [MENTION=6701872]AaronOfBarbaria[/MENTION] said. A compendium of traps, hazards, and hex-maps would be useful, but I'd like to see a lot more instruction to help DMs run engaging exploration challenges.
Any advice as I have been impressed with some of your scenarios you put up on the WotC boards. I have run adaptations of 2E The Night Below (part 1 Evils of Haranshire), X1 Isle of Dread and elements from Paizo's Kingmaker in 5E. PCs had fun which is the main thing but it was really easy mode of them.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.