Any way to make "Fire" Effects Linger or Trigger & Linger?

As in post title: I'm looking to make an effect occur and linger when my players cross a rock bridge over a lava lake so that lava debris cascade overhead. Instead of having to keep pressing the effect button, I'm hoping to just have the lava "fire rocket" effect linger. Is there a way to do this?  I've searched the forums and googled, but I can't find the answer. First time poster; long-time lurker - apologies if I'm in the wrong place/it's a stupid question. I beseech thee: impart your knowledge, oh Gods of Roll20 arcana.

There are 2 possible ways, both are available with Roll20 Pro subscription (not on Plus or Free). First way is "Custom FX" and you can program the duration. Details on this Help page, <a href="https://help.roll20.net/hc/en-us/articles/360037258714-Effects-FX-Tool#h_01H9J693TXW61T23R2H2MS982J" rel="nofollow">https://help.roll20.net/hc/en-us/articles/360037258714-Effects-FX-Tool#h_01H9J693TXW61T23R2H2MS982J</a> 2nd way is API Mod scripts, install and try the Mod called PageFX --- it can do lingering FX.&nbsp;

Alternately, if you search the marketplace for animated lava, you will find a number of animated effects that you can drag and drop on your map. If you want it to appear triggered, put it on the GM layer and move it to the token or map layer when you want it to appear.