RNG means random number generated (commonly used in games). So he meant he’ll fire randomly so the clown can’t read his attacks.
Also from the intro, it seems you drink potions to advance to the next sequence. Maybe that’s what he meant by “Clown potion”
Also the director said these 3 episodes were very fast paced in order to meet a certain point in the story from the source material under their contract. So we’ll see if it gets less confusing later lol