For this achievement I used the 4th level of the game "The Ramparts".
*For this method you need to start on the second or third wave as flying enemies spawn towards the end allowing you to fail whilst using the full time of the wave to hit traps.
*The second wave is recommended as the first wave is too quick and easy to fail and waves past the second feature bosses which take your attention away from the traps.
*You want to fail and repeat the wave as you will have to replay a mission anyway because this achievement can't be done in a single game, therefore just restarting the wave is quicker.
*I counted around 15% progress each wave restart so you will have to play this wave 6-7 times.
*It's also important to note that for this achievement to progress you can only trigger traps during the combat phase.
During the build phase you need to build a defense that can kill ground enemies whilst not affecting flying enemies. So build what you want without having ballistas, poison dart or frostbite towers facing the wyvern spawn and obviously don't use the sky guard towers entirely.
Here is my setup-
https://imgur.com/a/ah8thfz Once you're in the combat phase you must kill the 3 flying enemies at the beginning of the wave as they will end the wave early.
3 beginning wyverns shown here-
https://imgur.com/a/AHxAkmU Then you can start triggering the 4 dragon oil traps around the map in a near circular motion as your defence should be good enough to kill ground enemies by themselves.
4 dragon oil traps shown here-
https://imgur.com/a/81818R8Finally at around the 30 mark a group of flying enemies will spawn and will attack the door controls stopping the counter at 6, let them destroy the controls allowing you to fail and repeat the wave using this method until finished.
Final wyvern step shown here-
https://imgur.com/a/lbgCCo0Yes I understand you can get this through natural game progression, however I posted this method as a quick and easy way to get this achievement early.
I hope this helps.