I got Karthus on ARURF again, and finally noticed the enemy team of four mages was smart enough that after a couple double/triple kills and I made they all bought Zhonyas and used it to avoid my ult continously, forcing me to look at when they were fighting and were forced to pop it in order to ult instead of simply using it whenever it was off of cooldown... except for Tristana, who just died to it all the time. That game also helped me learn how to counter the Karthus cheese strategy, so I played a game as Tristana against one and rushed Edge of the Night, which allowed me to dodge a couple of his requiems (but not all due to the shield's arm time).
Still, it's kind of unfair how much better items with actives are in ARURF than ones with passives, which don't benefit from the mode's ludicrous CDR. I've found myself rushing youmu all the time as AD-based champions. Like, raw stats are always good, but I'd much rather have another ability to spam instead (FQC, Locket, Redemption, Ghostblade... heck, even Tiamat).
