Syndra, the Dark Sovereign

The first instant and sorcery you cast during your
turn costs {x} less to cast, where {x} is the number of
cards in your hand greater than 7.
When you cast an instant or sorcery during your
turn with mana value greater than 7, reveal the
top 3 cards of target opponents library, and they
lose life equal to the total mana value revealed
this way. This ability triggers only once each turn.
You have no maximum hand size.