Karthus ult change suggestion

Cooldown up to 450 seconds at all ranks. Cooldown reduction effect is halved for the spell. Channel time increased to 4 seconds. No longer is blockable by spellshields. Damage changed to 350/475/600 +135% ap +5/10/15% +1% ap current hp true dmg Now has a global quote on it. Now i don't know how will this affect him, but i feel like giving him an EXTREMELY strong ultimate that he can only use a couple times in a game really fits with his theme and gameplay. It could make the game for Karthus players a lot more fun because they will be getting multi kills almost every time they ult. It will also add depth to his gameplay, cause an ult with such a long cooldown has to be used effectively. His enemies will now have to basically not be chunked whenever he has his ult up, this automatically creates a lot of presence through the map, fitting his identity of bringing death to everyone no matter their resistances. It makes sense, cause his ult hits their soul, not their armor.

Now i know what u might be thinking: '' In late game if u dont have 3k+ health you will just instadie to Karthus ult, no counterplay!!!''. Well, a fix for that would be that you get some health, maybe like frozen mallet, rylais or rod if youre a mage, or use shields/shield items when u see him ulting. It is actually more telegraphed now, cause it will channel 1 second longer, have a more epic animation and a global quote. After this change, he would probably need a buff or nerf, but that are just numbers. I get it that this change is really crazy, but heck, Riot has done so many crazy changes lately it doesn't even matter. If this proves to be bad for Karthus' gameplay, it could easily just be reverted anyway.