Avalon, the Archivist

Avalon, the Archivist costs {x} less to cast,
where X is the number of cards in your
hand minus 4.

You have no maximum hand size.

Literature Wave — Whenever a creature attacks
you, if you have seven or more cards in hand,
tap that creature. As long as you have seven
or more cards in hand, that creature doesn't untap during your opponent's untap steps.

"Leave me be!"