hello.
the problem was, that this is our handwritten custom from old season, and there wasn't curse damage. side developers added this custom exclusively for us in new season client, but we forgot about curse damage at that moment.
thanks for remind, i will write about that to him. but now they're hard working with Season 17 bug fixes, so not sure, that they can fix it in fast way.
but anyway, on our server, magic power is more prefer for summoner. like meteor storm for sm, deathside for summoner, or dark side for rage fighter - this skills isn't a main skills for this classes. all classes main skills are singe target (meteor strike, aqua/fire beast, spirit hook).
thanks! π