Durin's Bane

Flying, trample (This creature can't be blocked
except by creatures with flying or reach. This creature
can deal excess combat damage to the player or planeswalker it's attacking.)
Durin's Bane costs {1} less to cast for each
creature your opponents control.
When Durin's Bane enters the battlefield, it deals
6 damage to target creature or planeswalker.