Underworlds has board game-styled boards, which is nice for quick setup, but far flatter than I’m used to. Fortunately, starting with Underworlds, GW has released plastic terrain kits with pieces for each of boards’ special hexes.
For blocked hexes, it’s very useful to have the terrain as truly blocked. For some of the hazardous hexes (the tentacle pit of doom), the piece is flat enough for a model to stand on. For others, you’ll need to move the marker off the hex. That makes them somewhat less useful and immersion-breaking. Ahh, well, it’s better than nothing.
I bought these markers from Secret Weapon, although I guess they’re no longer stocking them. The main reason was to act as dungeon dressing for Relicblade, but they’re generally useful for any fantasy setting.
The first set is this campsite. I especially like the eggs and sausage in the fry pan.
Next is this set of dropped weapons and packs. Would be useful for a relic.
Finally this group of treasure. I appreciate that each piece is unique.