Quote Originally Posted by DrWho2010 View Post
imo aren't those just gimmicks? and not really thoughtful lasting design?
Gimmicks can be good as long as they change up optimal completion strategy and are varied enough. For most modern dungeons the optimal strategy is to grab everything you can, pull them to the end of the area, group them up and then burn them down without factoring in what they can do.

For example, consider how a pull would be effected if a long corridor had one or more bombs or slimes that started casting a wipe causing self-destruct 30s after being aggroed after which they respawn.
How do pulls change when there exists a terrain effect or enemy ability that gives a long lasting damage resistance buff that can be removed by another terrain effect?
What happens when there is a stationary monster or object that spawns more monsters?