How to lower a flat to become another damaging flat?

[bioshockfan90]

Example: Upon getting key, ground lowers and the flat changes to lava, floor starts damaging.

[vita]

Actions 37 (W1) and 84 (WR) in vanilla.

[BigDickBzzrak]

Be sure to check this one out.

[Gez]

Look for those actions that "change texture and type" (might be abbreviated to something like "tx ty" in editor configs).