Episodes like "The Ricklantis Mixup" are already being hailed as all-time "Rick and Morty" classics, and Justin Roiland is a big reason why.

Seven episodes into “Rick and Morty” Season 3, fans and critics pretty much agree the Adult Swim favorite is having one of its strongest runs in its nearly four-year history. The season hit an undisputed high point on Sunday with the airing of “The Ricklantis Mixup,” which IndieWire’s Steve Greene gave an A rating and fans have already declared the best “Rick and Morty” episode ever. The half hour was an audacious look at police brutality, discrimination, and political corruption, but it was also a jaw-dropping showcase for Justin Roiland.

Roiland, who created the series alongside Dan Harmon, has been the show’s most valuable voice performer since the very beginning. As the man behind the voices of both Rick and Morty, Roiland has singlehandedly shaped the two defining personalities of the series. He has perfected the art of Rick’s aggressive and interruptive burps, and he has mastered all of Morty’s insecurities, from “Oh man” to “Aw jeez.” But never before has Roiland been asked to challenge himself the way Season 3 episodes like “The Ricklantis Mixup” have, and he has risen to the occasion to deliver the voice performance of a lifetime.

“The Ricklantis Mixup” is easily Roiland’s crowning achievement to date. The episode was set entirely in The Citadel, where the population is made up of various different versions of Ricks and Mortys. The episode’s plot jumped around at breakneck speed between various Citadel stories — a group of student Mortys searching for a portal to grant them wishes, a factory-working Rick snaps after he’s not given a promotion, an amoral Morty cop is paired with a newcomer Rick cop, and so on — each one giving Roiland the opportunity to slightly tweak the foundations of his voice work to build an entire world of oppressed and corrupt Ricks and Mortys.

Adult Swim

Roiland was the voice behind every single speaking role in the 22-minute episode (Jeff Davis helped out with some voiceover in the pair of fake commercials), and it’s a testament to his skill that different versions of these characters felt very much like unique creations, each working against the system in very specific ways. The amoral cop was such an aggressive shift away from the meeker Morty we all know and love that it was startling to watch him verbally abuse people. In instances like these, Roiland’s voice work embodied the very themes of the episode. The power of enforcing the arbitrary rules of The Citadel turned this Morty into a raging force of discrimination. In other parts, Roiland got the chance to let loose as Fat Morty, Slick Morty, and Creepy Morty, each one given a very small nuance in vocal delivery that made the episode as entertaining as it was socially conscious.

Read More: Every Episode of ‘Rick and Morty,’ Ranked

Beyond “The Ricklantis Mixup,” Season 3 has continually given Roiland the chance to flex his vocal muscles. In the outrageously funny “Rest and Ricklaxation,” Roiland was tasked with playing doppelgänger versions of Rick and Morty, each subverting the other’s personalities. Toxic Rick was a character on an aggressive adrenaline rush, while Toxic Morty was so self-loathing he was on the edge of a breakdown. Their real world counterparts were the opposite: Rick was shockingly considerate and Morty was jacked up on self-confidence.Hearing Roiland use a more delicate and considerate tone to channel Rick’s toxic-less self was a Season 3 highlight. The episode forced Roiland to experiment with the personalities he’s established over the series’ run, only adding to the “Rick and Morty” comedic toolbox.

Plus, who could forget about “Pickle Rick?” Roiland may not have used a different vocal style in that episode, but it proved his ability to mint classic catchphrases almost instantly. Or what about Morty beating up opponents with his newly-acquired muscular arm in “Rickmancing the Stone?” Morty’s cockiness inside The Blood Dome and his eventual shrieks of terror were reactionary gold. “The Ricklantis Mixup” set the bar sky high for the final three episodes, but something tells us Roiland and the rest of the “Rick and Morty” crew have more than a few surprises in store.

“Rick and Morty” Season 3 airs Sunday nights at 11:30 p.m. ET on Adult Swim.

Sign Up: Stay on top of the latest film and TV news! Sign up for our film and TV email newsletter here.