MTG Salvation

Hi there! Lately I had a problem with stacking spells. My friends and I were playing and someone cast fumigate and my other friend cast heroic intervention, after the heroic intervention resolve the caster of fumigateactivated bonds of motality. Can he do that or it have had to be done before with him holding priority and then passing the priority to have the effect to remove the indestructibility? It seems a pretty obvious question, but I came back to magic after 12 years so I'm not so sure what was right at the time.

Each time a spell or ability resolves off the stack, each player must pass priority before the next spell or ability on the stack gets a chance to resolve. So, yes, he can activate Bonds of Mortality after the Heroic Intervention resolves and before theFumigate resolves.