The idea is pretty basic and simple,an enemy with random based movement that auto cast a vortex bomb-like attack and it's counterpart, that pushes you away similar to a mender or some battlepods.
The frequency between each 'attack' would increase on each Tier.
There could also be 'totem' version that knights can pickup ad only affect mosnters. Some puzzles can be built around it.
When you pick up the 'totem' variant does it still have its effect taking place?
Also, slightly unrelated, but I was about to suggest a grappling hook weapon.