Eruth's Tome

Whenever you draw a card, you may exile a
card from your hand with a tome counter on it.
At the beginning of your end step, put all cards
with tome counters on them into your graveyard.
You may cast cards from among cards you own
in exile with tome counters on them.
{1}, {t} : Exile the top card of your library with
a tome counter on it.