Unfortunately, this room was already set up as a trap by Patchouli.

Thus Reimu and Marisa were trapped in this barrier.

Her plan is to defeat all three of them at once.

Patchouli's Barrier has 2 factors, which are the "Separate", which captures prey into a room, and the "Seal", which nullifies prey's abilities.

Patchouli's actions were actually considered against the rules, but the "lie" she used is "I will follow the rules", therefore she was able to carry out her strategy.

Each and every person can only defeat one person. But I have broken this limit.

I can even take out all of your team members at once if I want to.