Artika went into the tower with Nyctri because Nyctri was the only one that she could rely on. With Nyctri by her side, even an Executive wouldn't be able to handle her on their own. Not only Nyctri, but she also had an army of spirits and dead souls on her shoulders that she could summon whenever she wanted.
"A hidden dungeon on this floor? I have never thought there's a place that even spirits hadn't explored," Nyctri said as she walked next to Artika. "But that's also interesting hearing about Players unable to clear it or remember anything they encountered in that dungeon," she added.
"I'm interested in that dungeon as well, and I believe it's one of the few dungeons that Arsen couldn't find, or it might be a trap to lure us the descendants of the heroes," Artika responded as she heard whispers from the spirits and dead souls about Players that were sighted not far from her.