Chandra's Volcanic Temper

(You may cast a legendary sorcery only if you control
a legendary creature or planeswalker.)
Chandra's Volcanic Temper deals X damage to
each creature your opponents control.
If X is 4 or more, this spell has cascade and
wither and can't be countered.
If X is 8 or more, this spell has cascade. Put four loyalty counters on each Chandra planeswalker
you control.