Killian, Ink Duelist/You’re Confronted by Robbers question.

Probably a pretty easily answered question but how does \[\[Killian, Ink Duelist\]\] interact with \[\[You’re Confronted by Robbers\]\]? I would imagine the cost reduction only occurs for the \*Stall for Time\* mode but I’m curious as the spell could choose the other mode as well. Just wanted to double check!