Maxwell Cannon

When Maxwell Cannon attacks for the first time
each turn, untap it. After this phase, there is an
additional combat phase.
{2}{r}{t}: Maxwell Cannon deals damage equal to
its power to target creature. If the creature would
be destroyed by this damage, deal an additional 1
damage to all creatures that player controls.
{2}: Exert Maxwell Cannon and place a +1/+1
counter on it.
So anyway I started blasting.