Tetra Spiritdancer

Whenever a nontoken Aura becomes attached
to a creature you control, create a 0/1 white and
blue Spirit creature token with flying, then
create a token that's a copy of that Aura and
attach it to that Spirit.
Whenever a Spirit you control dies, if an Aura
you controlled was attached to it, draw a card.
When Tetra Spiritdancer leaves the battlefield,
exile all Aura tokens you control.