I noticed at the file:
stonehearth/services/server/game_master/controllers/encounters/destroy_entity_encounter.lua
Line 120:
local delay = rng:get_int(info.random_delay.min, info.random_delay.min)
As you can see, it is getting a random value from info.random_delay, but both the min and max are the same.
This values are set in the json, and specifies the random delay an entity has before being destroyed and an effect started (like goblin on fire when despawning)