Without a doubt, Ret-Talus needs bodies to sacrifice, and while Carriers are the best method of getting those bodies, the truth is that often there aren’t enough reasonable targets for Infect. When that is the case, Hellfire Cultists happily sacrifice themselves for the cause.
Cultists are a very core part of Ret-Talus’ strategy and you will be hard pressed not to summon all 4 every game. They are not only perfect bodies for Ret’s shenanigans, providing extra value in their sacrifice, but are great for blocking front gates, poking high damage targets in great positions and covering positions that need to be blocked but with a disposable unit, like the side of a gate or the side of a champion.
Even on their own they can often generate great trades as not many units can trade efficiently with them, thanks to the damage they do when killed compounding their regular ranged attack damage.