Do you think you look at how the "i will tear right through you." mechanic works?
By fixing the it you have essentially made melee unviable to use at the boss because you arnt able to attack kerapac from the edge of the arena because you cant lure him close enough to the edge and attack him at the same time.
The jump mechanic makes you need to surge arround making it very hard to position kerapac near an edge on the final jump while also dodging it.
This also discourages moving during the lightning phase incase you move kerapac away from theedge leaving the only option to use a turteling cade.
My suggestion isnt to put the rift all the way to the edge which disproportionately effects melee players but a set distance behind the character with it being capped out at the edge.
This would still reward edge placrment but also wouldn't be the end of the world if you were melee either.
No offence but i doubt i will be going back to this...