Thread:Shikifan/@comment-29427540-20180524160957/@comment-4802891-20180630030327

There's still a decent explanation as to why they qualify as a summonable spirit though :

- Both Shiki are linked to the Root

- Chloe's existence is(was?) tied to the Archer Class Card, making her something similar to a Servant

- Irisviel & Illyasviel are homunculi "weaved" to use Heaven's Feel. They are magical beings as powerful as Servants -- in term of spiritual energy at least

- Fujino... you got me there