Ultimate Revolution

Double nuke.

Ultimate Revolution makes Karthus game-warping with near-constant double-ult windows.

Sion's R code conflicts with Ultimate Revolution: after casting R, he's CC-immune for the rest of that life — even his zombie state stays immune. Pair with crit items and dive freely. Cast R early to lock in the permanent CC-immunity buff, then go ham.

Ult has high AP scaling and deals magic damage.

Crit chance + Death's Dance — abilities grant shields based on crit, while Death's Dance converts 30% damage into bleed that the shields absorb. Keep ability frequency high and you maintain a permanent 30% damage reduction.

Ultimate Revolution bug is patched (no more 4 R's), but you still get one R per life — pair with the suicide build for monster output. This style doesn't need Plague's ult haste — build pure magic pen / AP for max R damage. Strongly recommend Final City Transit synergy.

Use hexes to slash R's CD. Take any R-CDR hex; Ultimate Revolution is even better.

High damage, good tolerance, long R cooldown.

Once Void Rift is in hand, stack magic pen — damage explodes. Pop E snowball into the pile; main damage comes from Void Rift, so magic pen is priority. Liandry's can be skipped for Rabadon's.

Best Scope ADC.

Exploits a bug where revival passives reset Ultimate Revolution. Cast R at the start of a teamfight, die, revive, then fire two more ults — three waves of CC and burst per fight thanks to Zaahen's natural mobility. Watch the revive timing so you land safely back in.

Zilean R on himself: while waiting to revive, Ultimate Revolution treats him as already revived, immediately refreshing R. Cast it in time and you can perma-revive yourself, untouchable. R-on-self is mandatory to keep the loop; extra ability haste goes into Q poke.

R is sustained AoE healing — pair with Circle of Death for huge damage.