U could rework it to "easy to check places that turn easier a fiendish hunt" and talk about places like shrine portals, forgotten knowledge portals, barkless cave, etc, there are "key places" where u can say for sure or almost surely that a mob belong to a hunting places rather than all others.
In the other hand u could ask for the places with more chances to spawn a fiendish, talking about mob density around tibia or so.
but talking strictly about a pattern is really hard, because what determinate if a mob is influenced or not seems to be rng, a proof of that are unreachable fiendish, doesn't make sense that specific fiendish could appear in specific places when there are mobs that are simply unreachable no matter what and cipsoft says there's not too much they can do because of how the system work