Gravemore, The Grave filler

Whenever a creature your opponent controls
dies from blocking Gravemore, The Grave filler
choose 1
Put a +0/+1 counter on Gravemore, Trample
counter, Vigilance counter, {t}-Pay 2 life draw
1 card counter, other target demon gets +1/+1
counter, other Target Octopus gets +1/+1
counter, Firststrike counter