The Zillo Beast " The Zillo Beast " is the eighteenth episode of of the . It aired on April 3 , 2010 in the UK and on April 9 in the US . Official description . " The Republic ' s new super - weapon awakens the fearsome Zillo Beast of Malastare . Now the Jedi must devise a way to contain the deadly creature . " Plot summary . In hopes of obtaining fuel from Malastare , Mace Windu , Palpatine ( via hologram ) and Anakin Skywalker discuss the potential effects of the Electro - Proton Bomb , the Republic ' s latest superweapon , worried that the bomb could affect their troops as well as the droid army . Dr . Sionver Boll , the scientist who constructed the bomb confirms that it will not harm any Republic forces or Doge Urus ' people . Its effects will only work on droids and all the probabilities have been assumed . While Windu remains wary of the " improbable " and wishes to find another way , Palpatine insists the bomb is the last chance to secure a Republic victory . Windu and Anakin observe the outnumbered Republic and Malastare forces as they march toward the advancing Separatist forces . At the Separatist side , the tactical droid gives the order to attack . Captain Rex , clone troopers and Dug soldiers and Cavaliers on insectomorph s struggle to hold their ground , even as Hyena bombers soar overhead . Eventually the Republic orders the electro - proton bomb to be dropped on the massive Separatist force . The pilot drops the bomb , annihilating the Separatist forces with a massive blast . The blast is followed by an EMP which cuts off power to Palpatine ' s transmission , the clone tanks , and short - circuits Anakin ' s prosthetic arm , but leaves the clone force and the Dug soldiers unharmed . As the troops celebrate their victory , the ground starts breaking apart and sinking beneath their feet . The clones and Dugs flee with Rex , barely making it onto the ledge . However , some clones fall into the sinkhole , and Anakin dispatches rescue teams to locate the trapped soldiers . After losing contact with the rescuers , Mace Windu and Commander Ponds decides to investigate and look for the missing troops , while Anakin ratifies the Treaty to authorize fuel purchase from Malastare . Dug leader , Doge Nahka Urus exclaims his happiness for their alliance while they wait for the rest of the council to arrive and ratify the treaty . Meanwhile Windu finds handmarks and a clone helmet in the sinkhole when the clones find the rescue team and some of the troops that fell in the hole ; one of the traumatized survivors speaks of something down in the chasm with them . Windu , Ponds and troopers Hawkeye and Trapper begin searching elsewhere . Windu asks Anakin to come down and help , which Anakin preps his fighter and excuses himself . As they advance upon a ledge , Windu and the troopers feel the ground shaking as the massive head of a huge reptilian creature turns and roars at them . The clones fire at the beast with no effect . It shakes them off and chases them until Anakin distracts it by flying in circles , allowing Windu and the clones to escape . Anakin is surprised , and is caught off guard when the beast hits his fighter and he crashes , ejecting just in time . He strikes the monster with his lightsaber , only to find that its armor - like scales are virtually impervious to even his lightsaber . He leaps on the top of the beast ' s head and notices gaps in the armor which a well placed shot could penetrate it before jumping on R2 - D2 and rocketing out of the pit . After making his surprise exit , Urus arrives and explains that the creature is a Zillo Beast ; they were the dominant life forms on Malastare before his people arrived , and preyed upon the early Dugs . Urus states that when his people started harvesting fuel , the Zillo Beasts began to die out . It was believed that they became extinct . . . until now . The Dugs bomb the Zillo Beast fruitlessly while Mace and Anakin find Urus and the council observing the ancient script showing the weaknesses of the Zillo Beast . Windu and Skywalker argue that they will exterminate an innocent life form if they continue , but Urus threatens to cancel the treaty if they try to protect it . A talk with Palpatine shows that he supports the extermination of the Zillo Beast , but Dr . Sionver Boll and Anakin additionally support the idea to preserve it for replicating its seemingly impenetrable armor for military use and propose an idea to stun it in the gaps of its armor using Stun Tanks . When it is fully stunned and weakened , it would appear dead , but still be alive in stasis . The Dugs would assume it is dead and sign the treaty , while the Republic could move it to a secure location before it reawakens , where they can study the creature and possibly copy the armor . The Stun Tanks roll out to the pit where Urus is glad to see the events move in his favor , but his method is already working . He orders the Dugs to empty fuel lines into the pit . Urus explains the fuel is lethal to the Zillo Beast and should kill it , but Windu warns such an action will only enrage the Beast further . Windu urges Urus to stop and then threatens to kill him unless he stops , yet the Dug continues to oppose Windu , stating that he too is an innocent life form . However , Windu ' s warning proves correct when the provoked Zillo Beast climbs out of the hole and goes on a rampage , destroying everything in its path . It climbs up and the Stun Tanks open fire , seemingly to no avail . It swipes and destroys several tanks , causing Anakin to order backing up to avoid it . After a rampage , concentrated fire from the tanks start to weaken the Zillo Beast , and it eventually collapses , incapacitated . Sent into a deep coma by the cannons , the beast appears to be dead . Urus signs the treaty , and Malastare joins the Republic . Palpatine orders the Zillo Beast to be shipped to Coruscant for study , a matter for which Windu expresses concern . The episode ends with four LAAT / cs picking up the Zillo Beast to bring to Coruscant for study .