Having had directed the first installment of the Starz mini-series Spartacus: Gods of the Arena, "Past Transgressions", Warn was hired as a director for the sequel series Spartacus: War of the Damned. He ultimately directed eight episodes ("The Thing in the Pit", "Great and Unfortunate Things", "Kill Them All", "A Place in This World", "Sacramentum", "Wrath of the Gods", "Wolves at the Gate", "Mors Indecepta").[citation needed]
In winter 2014, Warn directed his first episode of the DC Comics produced Green Arrow origin series Arrow, which was episode 19, of season 2, "The Man Under the Hood", and featured characters crossing over from the series' impending spin-off, The Flash. Warn directed the third episode of The Flash's first season, "Things You Can't Outrun", which featured the introduction of future-superhero Ronnie Raymond.[citation needed]
He directed the 8th episode of Arrow's 3rd season, "The Brave and the Bold", which again featured a crossover event with The Flash. It also introduced the supervillain Digger Harkness/Captain Boomerang. His next episode was with the season's twelfth, "Uprising". It explored the motivations and genesis of The Dark Archer/Malcolm Merlyn. He directed the 17th installment of the year, "Suicidal Tendencies", from a script by co-producer Keto Shimizu. It saw the reformation of Task Force X, with new member Cupid/Carrie Cutter; and explored the past of Deadshot.[citation needed]
in 2023 Warn executive produced and directed for the NBC series, The Irrational.[5]