She is the only champion who can summon an enemy unit (Vessel).
Zoologically, Illaoi does not summon Nagakabouros' tentacles , which were supposed to be smooth all along and have suckers only at their distal clubs; instead, she summons the Goddess' arms with suckers along their length.
Illaoi's worldview expresses that everyone must follow their dreams no matter how brutal they might be.
But if while doing so someone becomes so passive or so demotivated to keep on pursuing their destiny that their soul starts to stagnate, then Illaoi will give them a Harsh Lesson in order to encourage them to get back on track.
This brand of tough love will end in one of two ways: someone passes their Test of Spirit and is back in 'motion' or they fail and, as a result, their energy returns to the universe so that another lifeform might make better use of it.
Serpent Islanders aren't aware of other religions (even though Nagakabouros isn't their only god) so they've never needed a name for their faith.
Indigenous creatures from their home isles are used as religious symbols in the same fashion Christianity uses lambs and doves.
They always share food with guests (especially fruit) but eating without offering to share is a huge insult and an overt threat in their eyes.
When Illaoi conducts a Test of Spirit she rips only one of the Vessel's many incarnations from throughout their lives.