The Infinite Sacrifice

The Infinite Sacrifice is the fourth episode of Ben 10: Infinity.

Plot
Ben as Humungousaur and the rest of the team are fighting a robot in the middle of the streets. After the robot takes out Kevin, it begins strangling Humungousaur. So Ben switches to Infinite Humungousaur to fight the robot, and proceeds to annihilate it, both Gwen and the Robot beg Ben to stop only for Ben to angrily shout out that he's not Ben.

Suddenly Ultimate Humungousaur attacks Gwen and Kevin, Gwen gets worried and notices that Ben's eyes are red. She tells Kevin that she thinks that Albedo might be controlling him, but Kevin thinks he just hit his head.

A conversation between Ben and Sentient Infinite Humungousaur follows. They keep arguing about whose body it is. Kevin gets annoyed and hits Infinite Humungousaur with a car so hard that he flew far away. Gwen thinks she could turn him back to Ben and uses her spell book to find the right spell.

After she uses the spell they see Ben (no longer Infinite Humungousaur) hitting himself with his eyes still glowing red. Gwen uses a sleeping spell to put him to sleep but he turns back into Ultimate Humungousaur. Kevin ties Ben up with metal cables and Gwen calls Dr. Borhez, a therapist, to see what's wrong with Ben.She asks him if he has issues with his mom when he was young. Sentient Ultimate Humungousaur replies that his mother tries to eat him before he even hatched (Sentient Infinite Humungousaur likely refers to the simulated worst-case scenario that triggers the species' evolution in the Infinitetrix). She tries to hypnotize the two personalities so that they can resolve their issues in their sleep and asks what he dreams of.

Sentient Infinite Humungousaur answers and says that he's going to kill Ben. He suddenly wakes up, breaks his arm free from the steel wires and chokes himself, attempting to kill Ben. His eyes glow green and Ben shouts out that he's killing both of them. Dr. Borhez gets scared and runs away asking them to pay for her work later.

Ben starts saying that his head is hurting. Sentient Infinite Humungousaur glows red and Ben disappears, and leaving behind the Device apparently turned off. Ben is sucked inside the Infinitematrix, thinking that he is dead.

Meanwhile back to Gwen and Kevin, Gwen argues with Kevin about how to get Ben back. Kevin figures out that Ben is inside the Ultimatrix. Gwen thinks that they should go in after Ben but Kevin thinks that they would be trapped in forever. He decides that she can take the risk if she wants to, but she has to be careful so she sent her Anodite astral projection form into the Ultimatrix, while he goes and finds Azmuth for help.

Back to Ben, he is convincing himself he cannot be dead, because of his heroism and his handsome face and charms, when suddenly a short earthquake comes and from under the earth come out Sentient Ultimate Echo Echo, Sentient Ultimate Spidermonkey, Sentient Ultimate Swampfire, Sentient Ultimate Cannonbolt, Sentient Ultimate Big Chill and finally Sentient Ultimate Humungousaur.

Ben is shocked and Sentient Ultimate Humungousaur wanted to kill him to set the Ultimate Forms free. Ben quickly explains that they can't do that because they are all him. Ultimate Echo Echo calls Ben a liar, and screeches at Ben. Sentient Ultimate Swampfire said that they have brains and hearts like any other life forms have and that they are all alive.

Sentient Ultimate Spidermonkey webs up Ben and Sentient Ultimate Humungousaur drags him away, intending to throw him into a fire pit which will kill him and set them all free. Ben turns into Ghostfreak to free himself from the web and tells them that they could try all they want. He tries to posses Ultimate Humungousaur, but is not able to.

Sentient Ultimate Big Chill uses his ice flames on Ghostfreak to freeze Ben (Ben as Ghostfreak couldn't escape as both of them were intangible), so Ben turns into Heatblast to melt the ice, then transforms into Brainstorm and runs away. Ben transforms into Diamondhead and fights them. They all hit him together, so he is forced to turn back to Ben.

Gwen's full Anodite form comes and takes them out to save Ben. Ben says that he had enough of being nice to them and turns into Way Big and throws Sentient Ultimate Big Chill and Sentient Ultimate Echo Echo into an Ultimatrix like building and slams the others down into the ground.

Sentient Ultimate Humungousaur calls out a retreat, Sentient Ultimate Big Chill questions his retreat idea but decides to do it anyway.

Meanwhile Kevin was flying the Rust Bucket 3, approaching Galvan mark II when a giant hologram recording of Azmuth's head appears warning that if the unidentified ship came any closer, it would be destroyed. Kevin thinks that nothing will happen, but although he was able to dodge the automatic security system, he crashed the Rust Bucket 3 and blew it up.

He saw that Azmuth's tower is close but when he got closer to the door, a big Galvanic Mechamorph came and told Kevin he can't pass, so Kevin got ready for a fight. Back to Ben (as Way Big), he was walking around looking for a way out with Gwen flying next to him.

Ben asks Gwen "what is with the glowy body". She tells him that her astral form was the only way to get into the Ultimatrix. Sentient Ultimate Spidermonkey captures Gwen in a web, but she just burns it off. The Ultimatrix times out and Ben turns back into himself, so the Ultimate Forms ambush him and take him by force.

Gwen tries to get closer to save him but Sentient Ultimate Echo Echo throws his sonic disks at her which distracted her. Back to Kevin, he is still fighting the Galvanic Mechamorph Guard. Kevin was getting defeated but during so, he tries to explain to Azmuth that Ben saved the world countless times, he said so that he could let him in to save him, his best friend.

Suddenly he sees Azmuth behind him telling the Galvanic Mechamorph to leave and tells Kevin that he will help. Back to Ben, Gwen was distracted by Sentient Ultimate Echo Echo's Sonic Doom attack. Ben was about to be thrown in a pit of fire by the Ultimates so that they could be set free.

Gwen suddenly gets really angry and blows up the sonic discs. She starts unleashing more of her immense Anodite power, But Ben begs her to stop, because she could lose her humanity. She says that she will no longer be under an immense power surge (so she gets to keep her humanity) and tells Ben that she is going to destroy all the Utimates.

The Ultimates realize their fate, but just before Gwen destroys them, Ben orders her to stand down. He willingly wants to ultimately sacrifice himself so he can set his Ultimates free. Ultimate Humungousaur grabs Ben, takes him to the pit of laser fire. Ben asks Sentient Ultimate Humungousaur whether he could have a last word with Gwen. He hesitates but yet he trusts that Ben won't trick them.

So he lets him go to Gwen. He tells Gwen that he has to die. Gwen begs him not to do so, but Ben tells her to keep quiet. He said that a true hero will sacrifice for the sake of others and that he must die, if he wants to set the Ultimate forms free to live their lives and then gives Gwen a goodbye kiss on her forehead.

He walks slowly to the pit of fire with the Ultimate forms around him cheering with the word "Burn". Before Ben jumps in he stops to tell them that he never intended them to suffer. He takes one last breath, waits a little and then he jumps in.

The camera showed him waking up out of the Ultimatrix with Gwen, Kevin, the ultimate forms and Azmuth around him. He was confused and told Azmuth that he died, Azmuth tells him due to his heroic sacrifice, the Ultimatrix set the ultimate forms free and spared Ben's life.

He also tells Ben, while fixing the Ultimatrix, that the glitch that caused the Ultimates to gain conciousness has been removed and they will now be a reflection of Ben as with all his transformations. They tell Ben that they are sorry of what had happened in the Ultimatrix, but Ben said he contained no hard feelings. Azmuth creates a portal to take him home and the Ultimate Forms to a planet that they would live in peace on.

Before they all left Sentient Ultimate Humungousaur apologizes to Ben and states that he wasn't as bad as he thought before leaving himself. Ben seems proud of himself by the expression on his face at the end of the episode and Kevin invites Ben and Gwen for a visit to Burger Shack. Gwen is surprised but Kevin says that it's the least he can do for his "girlfriend" and his "best friend".