Time Devour

This spell costs {x} less to cast, where X is the
number of spells cast this turn.
Split second (As long as this spell is on the stack,
players can't cast other spells or activate abilities that
aren't mana abilities.)
End the turn (Exile all spells & abilities from the
stack, including this card. The player whose turn it is discards down to their maximum hand size. Damage
wears off, and "this turn" & "until end of turn" effects end.)