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Vaulting > Trapper Priority
So, I had two areas where I could not understand how survivors were vaulting through my traps. I checked placement, and they were lined up perfectly. Then, I saw it in person. When someone did a medium vault against my trapper at a trapped window, on the side they were vaulting from, he got halfway through the vaulting animation before the trap sprang on him. On fast vaults, they could sometimes get away from the window fast enough with things like Lithe before it even checked the trap, on either side of the vault. The game is currently giving the vaulting animations of survivors priority over the presence of a trap, letting them vault traps that are at windows. You have to put the trap a bit further back away from the window to get it to work, but that also means it isn't as reliable, because it means they don't work on slow or medium vaults.