Start with a pressure plate and a dart thrower
Put a Pressure Plate on a tile enemies are likely to step onto, then connect it to the Dart Thrower you want it to fire. The plate is the trigger. The thrower is the device that does the damage. Starting with one of each makes it easier to tell which connection you're checking.
Verify the wire before relying on the trap
Select the Pressure Plate after wiring it. In Mossbomb’s official wiring screenshot, selecting the plate highlights its tile and draws a blue line to the wall-mounted Dart Thrower. The plate’s effect panel also names the thrower it triggers. Use the line to confirm the exact device, especially if there are several throwers in the corridor.
The screenshot shows a finished connection. Check the controls in your build for the action that creates it.
Put the trigger where the target will walk
The Pressure Plate tooltip describes activation when an enemy or a wild creature steps onto its tile. Put it on the route you expect that target to take, then check the selected plate again before building more links. A wire that reaches the right device is only part of the setup. The target also needs to cross the plate.
FAQ
Which device does the pressure plate fire?
Select the plate and check where the blue line ends. Its effect panel also identifies the linked device.
Can a wild creature trigger the plate?
Yes. The documented tooltip names both enemies and wild creatures as valid triggers when they step onto it.
Can I reuse these activation rules for a tripwire?
Malignus also supports tripwires. Check their own tooltip before planning around them, since the rule above comes from the Pressure Plate.