Rubius invokes the "Eenie, Meenie, Mine, Moe..." ability and asks the question out loud to himself:
"Now how in Habastly's name am I supposed to stop this thing? Where exactly on this contraption is the weakness of this heart?"
With that, he begins to search around the heart for anything that appears to be fueling it such as psionic ooze, magic items, clickers, etc.