Immobilizer 418 cruiser / Legends The Immobilizer 418 cruiser , also known as the Interdictor " - class heavy cruiser , Interdictor " - class medium frigate , Interdictor Dreadnaught , or simply the Interdictor , and sometimes colloqually as the Drag Ship , was a 600 - meter - long cruiser built on the standard " Vindicator " - class heavy cruiser hull ( later used for the Enforcer - class picket cruiser ) . Equipped with gravity well projectors designed to pull ships from hyperspace and / or prevent them making the jump to lightspeed , the Interdictor became a valuable addition to the Imperial Navy . Characteristics . Interdictor cruisers , like their " Vindicator " - class cousins , had the appearance of small Star Destroyers . However , their lines were broken by four large globes housing gravity well projectors . The gravity wells mimicked a large mass in space and thus restricted hyperspace travel . Nearby vessels were automatically prevented from engaging their hyperdrive , and any ships passing through the area via hyperspace were forced into realspace . As well as gravity wells , the Sienar design was also equipped with 20 quad laser cannons for short range combat against other capital ships and starfighters . The Interdictor ' s hull was nearly identical to that of the " Vindicator " - class heavy cruiser and could support several additional weapons depending on mission profile . Such modifications ( like those of the " Corusca Rainbow " , formerly the " Black Asp " ) included the addition of ion cannons used to disable pirates and small craft attempting to flee . Enemy fire was absorbed by a deflector shield created by more than a dozen shield generators . A variant of the Interdictor design existed , equipped with two large gravity wells rather than the usual four : a ship of this type appeared in Grand Admiral Thrawn ' s ambush of Luke Skywalker at Jomark in 9 ABY . Role . The Immobilizer 418 was developed as a counter to the Rebel Alliance ' s hyperdrive - equipped starfighters in particular , and hyperdrive - equipped vessels in general . This was primarily to counter Alliance hit and run tactics , where a small group of starfighters or light starships would emerge from hyperspace , attack preselected targets , and re - enter hyperspace before sufficient force could be brought to bear on the raiders . An Immobilizer at the site of attack , or able to access the area with a brief hyperspace jump , would be tasked to power up its gravity well projectors in an attempt to prevent the escape of the raiding party . Starfighter and capital ship support would then be used to eliminate the attackers , whose only options were to try to run for the edge of the interdiction field , or to attack the Interdictor and hope to inflict enough damage to disable the cruiser ' s influence . Either path would result in significant damage to the Alliance forces . Rebel pilots often mistook it for a miniature Star Destroyer when it was accompanied by Star Destroyers . It was only when they tried to escape into hyperspace that they realized it was an Interdictor . Interdictors could also be used when blockading planets or moons , such as Yavin 4 . Another duty of this class was to patrol trade routes . Freighters pulled out of hyperspace by an Interdictor would be in a position to have their cargo inspected . Interdictors were a welcome addition to the Imperial Customs assets , because while many smugglers and pirates wouldn ' t hesitate to outrun — or in some cases even outgun — an Imperial Customs Frigate , few would dare engage with a much more sizable Immobilizer 418 , its gravity wells and its two squadrons of TIE starfighters . Interdictors assigned to Customs duties — such as the former " Black Asp " — would often have some of their quad lasers replaced by ion cannons so as to disable and capture any ship resisting inspection rather than destroy them outright . Grand Admiral Thrawn was especially famous in connection with Interdictors for developing and refining a tactic that would be named after him — the " Thrawn Pincer " positioned the Interdictor ' s gravity wells along certain vectors . Other vessels — typically Star Destroyers — would be contacted , and would blindly execute a micro - hyperspace jump straight into the Interdictor ' s gravity wells , yanking them out of hyperspace near an enemy vessel . Much quicker than sublight movements , the Thrawn Pincer allowed reinforcements to be swiftly deployed on the battlefield and afforded a considerable element of surprise . Weaknesses . Although they were tremendous assets to any fleet , Interdictor cruisers suffered from some drawbacks . First and foremost , it took some time to power up and activate the gravity well projectors after the cruiser positioned itself and , once activated , the tremendous simulated mass they generated made the ship very slow and cumbersome to maneuver . While there was rarely enough time for an entire fleet to make the jump to hyperspace before a newly - arrived Interdictor activated its projectors , fast ships and starfighters could often escape to the edge of an active gravity well , and then make the jump to hyperspace . The gravity wells were also a large drain on the ship ' s energy reserves , preventing the optimal use of weaponry and shields . This flaw was exploited on several occasions . When enemy ships were able to inflict significant damage to the Interdictor , the captain was forced to choose between entrapment of the enemy and his ship ' s own protection . This flaw was compounded by the fact that Interdictors were poorly protected and armed for a capital ship of their size . Enemy forces could send a smaller warship , such as an Nebulon - B frigate or " Thranta " - class War Cruiser to weaken an Interdictor ' s defenses and quickly force it to power down its gravity wells to fend for itself . Although the abilities of the Immobilizer 418 were fairly effective against the missile launchers of the " Marauder " - class corvette often employed by the Rebel Alliance , the ship was also known for its notorious weaknesses against larger capital ships such as the Mon Calamari MC80 Star Cruiser and bombers such as the BTL Y - wing starfighter . Another problem was the fact that active gravity wells attracted space debris . An Interdictor could — and would — suffer external damage from larger pieces of such hazards . While most damage was minor — as the largest debris would be detected and fired upon by the gunnery crews — it was one reason Interdictors required more maintenance than many other fleet vehicles . Additionally , the engine and hyperdrive - specific areas of an Immobilizer ' s interior sections were crewed only by maintenance droid s , and were totally unprotected . Raiders and saboteurs were thus able to infiltrate and either disassemble or destroy the vital parts of the cruiser ' s propulsion systems . Due to their importance and weaknesses , Immobilizer 418 cruisers were usually found on the periphery of the battle they were affecting , escorted by larger and better equipped capital ships and starfighters to protect them from harm and deliver the necessary damage . Other Interdictors . While Sienar Fleet Systems ' " Immobilizer 418 " was the most common design of Interdictor , other ships made use of gravity well projectors . Kuat Drive Yards used the hull of an " Imperial " - class Star Destroyer to create the Interdictor Star Destroyer which was supposed to compensate for the Immobilizer 418 ' s combat weaknesses . The command ship used by Darth Vader immediately after the Battle of Yavin mounted large projector globes in the manner of the smaller cruisers . During the Yuuzhan Vong War , the New Republic launched " Mon Mothma " and " Elegos A ' Kla " , which carried improved interdictor equipment inside a normal Star Destroyer hull . The immense " Eclipse " - class and " Sovereign " - class Star Dreadnought s also carried projectors internally within their massive hulls . Interdictor technology was not completely limited to the Empire , however . Alliance forces made use of older CC - 7700 frigates , and scientists in the Hapes Consortium reverse - engineered the gravity - well projector from captured ships ; but rather than building bulky projectors , the Hapans fitted their Battle Dragons with launchers for charges known as pulse - mass mines , which produced much the same effect . However , pulse - mass mines could not be turned off or controlled like gravity wells , so this trapped the Hapans in the battle as well . Service history . The Interdictor cruisers were first manufactured by Sienar Fleet Systems two years before the Battle of Yavin . It was an Immobilizer 418 cruiser named " Assessor " that boarded Han Solo ' s " Millennium Falcon " , forcing him to jettison the glitterstim spice that he was smuggling for Jabba the Hutt and had the " Falcon " searched by Captain Tybert Capucot before Solo escaped once again from Imperial forces . Many Vindicator cruisers were converted to Interdictors . In spite of that , only a relatively small number was used against the Rebels . An Interdictor of the Imperial fleet was essential in the capture of Moff Kalast during the period of the Death Star construction . The Interdictor prevented the traitorous Moff ' s Star Destroyer from jumping to Hyperspace long enough for the Destroyer to be captured . An Immobilizer 418 cruiser was responsible for the elimination of the Deretta Destroyers , an Alliance to Restore the Republic starfighter squadron , sometime before the Battle of Hoth . The squadron jumped into the target area of an Imperial depot ahead of their main Rebel strike force , where they softened up the opposition . However , the Immobilizer ' s presence prevented them from escaping , and the Destroyers were wiped out before the bulk of the Rebel force could arrive . Between the Battles of Hoth and Endor , the Immobilizer 418 saw extensive action during the campaigns involving rogue Admirals Harkov and Zaarin and the threatened proliferation of TIE Defender technology . Aside from Thrawn , Zaarin was the only other Imperial officer to make frequent use of the Interdictor cruiser . Zaarin had the " Harpago " try to stop Darth Vader from warning Emperor Palpatine about the coup , then he deployed " Grappler " to trap Thrawn at the Rebel platform RS - 32 . In both instances , Zaarin ' s Immobilizer 418s were destroyed thanks to the intervention of Maarek Stele . The Immobilizer 418 was prohibitively expensive , reportedly costing more than an Imperial Star Destroyer , and produced in very limited quantities prior to the Battle of Hoth . By the time of the Battle of Endor , Sienar Fleet Systems had manufactured only a few hundred Interdictors ; by comparison the Empire had approximately 25 , 000 Imperial Star Destroyers . An Interdictor cruiser was once used by the Zann Consortium during a piracy mission above Bespin . During the Bacta War , the Interdictor cruiser " Aggregator " ambushed Rogue Squadron at Alderaan ' s Graveyard . After the Battle of Endor , the one time lieutenant Lon Donell turned to piracy and used the Detainer to raid New Republic shipping . During the Hunt for Zsinj , Admiral Teren Rogriss moved his flag to the Interdictor " Stellar Web " and collaborated with Han Solo ' s fleet to trap and engage Warlord Zsinj ' s " Iron Fist " at the Battle of Vahaba . These vessels would not realize their full potential until several years after Emperor Palpatine ' s death , when they became a key component in Thrawn ' s attempt to defeat the New Republic . The Grand Admiral , who commanded a large number of these ships in the Outer Rim Territories , would deploy them to ambush New Republic forces . He once used an Interdictor in conjunction with his flagship , " Chimaera " , in an attempt to capture Luke Skywalker . However , the Jedi eluded capture , by escaping " Chimaera " tractor - beam lock , racing out of range of the gravity - well projector , and making a quick jump into hyperspace . After Thrawn ' s defeat , New Republic technicians redesigned the Interdictor ' s gravity - well projectors , improving both their range and recharge rate . These new Interdictors , designated Immobilizer 418As , became one of the key components of the New Republic Defense Fleet during the Yuuzhan Vong War . During the Battle of Fondor , the New Republic supplied four Interdictors to the Hapan fleet . One Immobilizer was used with other antique vehicles in the construction of the Hidden Temple used by the Jedi as a secret refuge during and after the Sith – Imperial War , and at least one was used during the Evacuation of Dac . Behind the scenes . The Interdictor is almost always shown with its four gravity well generators represented by four complete globes , two on either flank of the hull . One early image of Thrawn ' s attempt to capture Luke Skywalker at Jomark , however , shows two hemispherical domes protruding along the centerline on the topsides , with two more by inference on the ventral hull . While at odds with most subsequent representations , this rendering is as consistent with the original profile view in the " Imperial Sourcebook " as the more familiar four - globe variant , and another depiction of the same events at Jomark also shows the same distinct type of ship , this time seen from below — thus strengthening the claim of this type to be a canon variant rather than simply a visual inconsistency . Some vessels such as " Binder " , " Constrainer " , and " Sentinel " were called " Interdictors " in the novels , and are presumed to be " Immobilizer 418 " cruisers . However , they were drawn as " Interdictor " Star Destroyers in the Dark Horse comic series . In " The Black Fleet Crisis Trilogy " , an Interdictor starship was described as an Interdictor Dreadnaught . This ship was later clearly identified as an Immobilizer 418 in its entry in " The Complete Star Wars Encyclopedia " . In the game " " , the Immobilizer 418 is designated as a frigate , along with a wide variety of other ships smaller than Star Destroyers , and is armed with four laser cannons . The vessel is strong against " Marauder " - class corvettes , whose missiles it can divert , but is weak against larger capital ships and bombers . Additionally , " The Official Star Wars Fact File " lists the Immobilizer 418 ' s length as 600 meters . However , this is inconsistent with the vessel ' s portrayal in " Empire at War " , in which the Immobilizer 418 is shown to be longer than the 752 meter - long " Acclamator " - class assault ship . The 1998 PC program " " includes a glossary entry for the " " Interdictor " - class cruiser . " However , as this entry indicates , the description is intended to apply to the Immobilizer 418 cruiser . As such , that description should be not be confused with the " Interdictor " - class cruiser of the " " game . " " likewise refers to the Immobilizer 418 cruiser as the " " Interdictor " - Class Cruiser . " In the " " series novel , " " , Jagged Fel refers to Interdictor cruiser , " Kagcatcher " , as an " Interceptor " . Early sources and videogames don ' t mention any complement , it soon changed to 24 TIE starfighters . .