WHY REMOVE IT ? What summoner spell should i take now as karthus??? Thin air? cmon its an indirect nerf to karthus without revive i cant charge in their team to lower them to embaracing lvls and quickly revive to get into teamfight and finish the job. I played karthus for long time and I find revive the most usefull summoner spell , since ignite is not that usefull on him cause you die then you kill....... PLease what should i use now?
I find that 
work well on Karthus if you don't like Ignite.
Teleport lets him gank other lanes or teleport to fights later in the game, which is nice considering the objective control he can provide. Also lets him teleport gank other laners if he has the opportunity.
Exhaust is useful for slowing your opponents (keeping them in range and making it easier to land Q) while reducing their damage. It's great for shutting down damage dealers later in the game, catching people, and protecting yourself.
Barrier can help keep you alive for better position yourself before dying and surviving against burst damage in lane.
It was a troll spell get ove rit
Unless you are looking to revive->R teleport is better.
While Revive will get you back in right away, it assumes you're going to die.
Teleport can also get you back into lane after a bad fight and provide global pressure on top of his already high global pressure. And you can do this more often. Revive's CD is long. Really long.
Overall, whatever you think Revive does for you, there are better options. And unless you're playing ARAM, suicide Karthus is not a viable strat. Remember that you're giving away a kill and up to 4 assists by doing that. It's a huge gamble.
It was good in dominion.
