Tavera, the Runecaster

At the beginning of your upkeep, you may pay
{2}. If you do, search your library or graveyard
for a Runestone card, reveal it, and put it into
your hand. If you search your library this way,
shuffle it.
{x}: The next time a Runestone you control
would deal damage to you this turn, prevent up
to twice X of that damage.