Astrid, the Pirate Queen

Whenever Astrid, the Pirate Queen kills a
creature, you may pay {1} to create a Treasure
token.
Astrid, the Pirate Queen gets +1/0 for every
Treasure token you control.
When you control 3 or more treasure tokens you
can reduce the cost of casting a vehicle spell that
you control by {1} for every treasure token you
control.