Yoda's best tutaminis feat which has been replicated by Mother Talzin and to a degree, even Galen Marek.
Not that it isn't impressive, but your false equivalence aside, Vitiate's lightning is so far beyond Nyriss' that it's a comparative joke. Nyriss, whose lightning was capable of incinerating one of the three most powerful Jedi in three hundred years, and Scourge who tanked Xedrix's lightning. Who despite suffering from age is still wanked to be the third most powerful Sith in the empire by his time besides the Emperor himself.
Nyriss' lightning being amped also isn't remotely relevant to Revan's raw power, infact it only makes Revan more impressive that he is doing this on a nexus that he states blocks his farsight abilities. Then add three centuries of him gaining knowledge and the fact he is stated to have further intensified his powers as of SOR, and we have a guy that isn't just ashing Nyriss tier Force users, he's likely twice that degree of strength and mastery. Factoring in that he is freely abusing his Force in balance powers and is drawing on the dark side without any hesitation.
He went from losing to a single smaller strike team at the Foundry, to barely being defeated by two much larger and much more powerful groups, who were aided by his other half's spirit. All whilst dragging his dead body around through sheer will power and focusing his powers on the activation of the Temple of Sacrifice.
Darth Marr is simply one source among many, both in-universe and out of universe, that state Revan was insane for even believing he can defeat Vitiate.
There's really no counter here.