Nova, Friend to Eterna

When Nova, Friend to Eterna enters the battlefield, create x "Shard of Tiangong" artefact
tokens. X cannot be more than 13.
{r}{u}{b}, {t}: Create a "Shard of Tiangong"
artefact token
Nova, Friend to Eterna's power and toughness
are each equal to the number of "Shard of
Tiangong" tokens you control.