For the first effect (gaining Life Points), it is the controller of “Granadora” who gains. For the second effect (losing Life Points), it is the owner of “Granadora” who takes damage.
When your face-down “Granadora” is destroyed, you take 2000 damage.
When your “Granadora” is destroyed and sent to the Graveyard, you can activate “Barrel Behind the Door” against the damage.
When “Granadora” is destroyed and sent to the Graveyard from the field, your hand, or from your Deck, its effect is activated.
When “Granadora”’s Summon is negated and it is destroyed, by “Solemn Judgment” or “Horn of Heaven”, the owner of “Granadora” takes the damage.
Netrep Rulings:
“Granadora” does not inflict damage if it is Tributed.