Games : I want to make a factions fall trap that is completely flush with its surroundings

I'm playing on a factions server and during pvp people regularly try to lure us into a trap, the traps are easy to recognize though.

So I've been trying to make a trap that I can disguise with the terrain but that is also bigger than most traps, to make it easier to trap people in it. Another thing that I'd like is if it is easy to operate for other inexperienced players in our team.

I tried to make one in my creative world but I got nowhere because I'm not the best with redstone and I have no clue where to even start.

Can someone help me with creating large, deadly traps that can be well hidden in the terrain?