Marcus Crassus is far craftier and more ruthless than we previously imagined. [Spoiler alert! If you haven't watched the "Decimation" episode of Spartacus yet, avert your eyes or continue reading at your own risk.] On Friday's Spartacus: War of the Damned, the deep plan that Crassus (Simon Merrells) conceived was finally revealed: Julius Caesar (Todd Lasance) would infiltrate Spartacus' (Liam McIntyre) group by disguising himself as a fellow (hairy, unwashed) rebel slave. So that's why Crassus didn't want Caesar to cut his hair! "I was so excited when I read Episode 4," Lasance tells TVGuide.com. "That's when the big shift happens with Caesar. This is one of the defining episodes, which triggers what plays out this season." PHOTOS: TV bad guys we root for Beyond his military genius, Crassus also revealed his merciless side when he punished his own soldiers who retreated after their botched attack on Spartacus by reviving the practice of decimation - one-tenth of them drawn through random lots would die by the hands of their fellow soldiers. In the end, son Tiberius (Christian Antidormi) was forced to kill his own childhood friend Sabinius (Aaron Jakubenko), who was one of the unlucky ones. Think that's brutal? The rebel side didn't do much better when it came to inner turmoil and bloodshed. Will Crassus' punishment make his point? Should Spartacus employ harsher practices like his enemy? What will be the fallout of the respective slaughters? Check out our burning questions from "Decimation" below: Will Crassus outsmart Spartacus? Planting Caesar behind the walls of Sinuessa en Valle isn't the first time Crassus has fooled Spartacus, who only now has realized that he was intended to intercept that fateful message long ago. This epiphany seems to have inspired Spartacus to finally take a more offensive strategy in order to dictate the narrative of this war. But this reaction only proves to demonstrate that he's still a step behind. He needs to be several steps ahead to pull even with Crassus. How effective will Caesar's cover be? It turns out that the dude isn't kinky after all! But that doesn't mean he's entirely sane. He mutilated his own leg to make it look like he cut off his master's brand in order for the rebels to accept him as an ex-slave. That's just so crazy and dedicated that we don't think he's going to break his cover accidentally. When he eventually reveals his true face to the rebels, it will be under his control and most likely when he's holding a weapon. PHOTOS: Best TV and movie characters with eye patches Can Nemetes (Ditch Davey) be trusted? That sneaky German is stealing from Spartacus! It's clear that his ideals don't quite line up with that of the rebel leader and that he's looking out for No. 1. Also, there's that great, prophetic line, when Nemetes assesses Caesar and says, "I believe his loyalties mirror my own." Can Gannicus (Dustin Clare) forgive Naevia (Cynthia Addai-Robinson)? Gannicus knows all about forgiveness, even when life-and-death mistakes are made, but Naevia didn't so much make a mistake as decided to ignore the facts and let her prejudice lead her to kill his friend Attius (Cohen Holloway). Since Gannicus prefers to drown pain in wine and women, we don't see him seeking out vengeance, but he will always hold that grudge that will affect his ability to trust her. Not a good omen for comrades in arms. Is Crixus (Manu Bennett) whipped? As one of Spartacus' rebels, Crixus definitely holds his own opinions, but it seems that it's Naevia's counsel that leads him astray. Love your woman, defend your woman, but for the gods' sake, don't let her affect your judgment when it comes to military matters. Alas, it seems that she holds more sway than Spartacus does, and that will come to a head (again) soon. "In the midst of all the chaos and all the war, the two of them really are the ones who speak the same language," Addai-Robinson says. "She guides him, he guides her. They really have that back and forth with each other that we don't really have with the other members of the group. You'll also see how that plays out." How will Tiberius recover from the decimation? "We were all fascinated by this idea of decimation, about killing every one in 10 soldiers for disobeying," executive producer Steven S. DeKnight says. "What we really wanted to do was show why that happened and the emotional impact of what happened." Since Crassus treated Tiberius as if he were any soldier and not his son, don't expect Tiberius to embrace dear old dad for the harsh lesson. No one can twist souls like the ancient Romans can, and punishments run the risk of teaching resentment and rebellion. PHOTOS: Winter TV eye candy BONUS HIGHLIGHTS Damndest Death(s): The rebels killed so many Romans that the streets of Sinuessa en Valle became one big, bloody Slip 'N Slide. And although watching defenseless, shackled people attempt to crawl away from being killed was hard, Sabinius' decimation execution was far, far worse. Not only did we share in Tiberius' psychological trauma of having to kill his BFF, but the slo-mo bludgeoning, featuring fountains of blood and various bones poking through flesh was drawn out to elicit maximum discomfort. Who's being punished here, the soldiers or the viewers? Uncle! Uncle! Rebels/Romans Say the Damnedest Things: Crassus: "One must appear as wolf to be welcomed by the pack." Brictius: "I do not see Gannicus among your nor cause to heed his b----!" Saxa: "I give cause, b----!" What did you think of Crassus' harsh lessons and Caesar's undercover job? Does Spartacus have a mutiny on his hands? Spartacus: War of the Damned airs Fridays at 9/8c on Starz.