An idea to rework Karthus's Requiem

Requiem: For 10 Seconds, Karthus gains Truesight and vision of all enemy champions. Lay Waste and Wall of Pain can be cast globally during this timeframe. If Karthus is in Death Defied, Requiem will heal him for 25% of the damage done to champions by Lay Waste. If he heals up to 80% of his maximum health, Karthus will resurrect after Requiem expires.

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Disclaimer: I'm just a random idiot speculating, as far as I know, Riot is planning to keep ignoring Karthus. -_-

So, Karthus is one of my favorite champions to play. I like his style, and yes I love using his ult. Requiem the Saltmaker. But as mobility keeps getting higher and higher and all-in early game damage gets more and more emphasized, I've found Karthus struggles to stay relevant a lot more than he used to. Basically, I'd be in favor of updating him to a more modern day standard of playability.

The problem with that? Karthus is unbuffable, and I think a strong case can be made to pin the blame for that onto his ultimate.

Requiem is oppressive to play against, it forces specific picks and builds, and in most cases it can render doing the intuitive thing and nuking the Midlaner pointless, because if Karthus dies in the middle of the teamfight all you've done is give him a free window to ult your entire team, and either blow all your defensives or nuke you from orbit so his allies can sweep in and cleanup.

And from the standpoint of the Karthus player, the ult takes up a LOT of his "power budget". Requiem's power level is why he's a passive farmer for most of the lane phase except for specific matchups. He can't get a stronger early game because it would mean global unavoidable damage hitting harder sooner, which is a really poor Enemy Player Experience.

So I had a thought to rework Requiem to keep the global damage identity, but give it a bit less power, so some of it can be shifted into his baseline kit and make him more well-rounded. Also comes with a buff to his passive, to put the defiance into it a bit.