In season 3 episode 14 we see Beast Titan transforming himsef along with an army of Pure Titans.
As far as we know, Pure Titan can be made using Titan Spinal Fluid and Beast Titan has an ability to control those made of his Spinal Fluid.
But how an ARMY of Pure Titans appeared at once if it needs to be injected manually? I tought he had a slight, imperfect control over his Titans, but is it actualy Fouding Titan level control that allow him to transform/untransform them at will?
Spoilers ahead. Be warned.
He most likely used gas which has his spinal fluid.
It was revealed in Chapter 110 how Marleyan soldiers spread gas which contains Zeke's spinal fluid to Ragako village. Zeke called it a Gas Weapon. He explained that any Subjects of Ymir who will inhale the gas won't be able to move and would lose consciousness. It was then shown how all villagers transformed when he screamed. He probably placed people who inhaled this gas surrounding Shiganshina. He then screamed then transformed alongside with them.
