Black Swan, Lady Apocalypse

Whenever you cast a spell, add {r}. Until end of
turn, you don't lose this mana as steps and
phases end.
Creatures you control can boast twice during
eachof your turns rather than once.
"Empires have collapsed. Kings have fallen. Men
have perished. Worlds have ended... and that's just
the beginning... everything dies."
—Black Swan