So, suppose I declare a 3/1 attacker. Then the defender declares a 1/1 to block it. Once it is declared a blocker. May I then cast a spell or activate an ability to kill said blocker, before combat damage is calculated. Not only saving the creature, but also, now having no blockers, do the 3 damage with my attacking 3/1? Or is it just a save, but since a blocker was put there, I then decide to save my homie, and slay the beast, but deal no combat damage to player? Or door C, I can't intervene and do damage there and must watch all crumble to dust?