Sorrow's Path

The first ability can target any two blocking creatures a single opponent controls. Whether those creatures could block all creatures the other is blocking isn’t determined until the ability resolves.

When determining whether a creature could block all creatures the other is blocking, take into account evasion abilities (like flying), protection abilities, and other blocking restrictions, as well as abilities that allow a creature to block multiple creatures or block as though a certain condition were true. Take into account whether those creatures are tapped, but not whether they have costs to block (since those apply only as blockers are declared).

A “blocking creature” is one that has been declared as a blocker this combat, or one that was put onto the battlefield blocking this combat. Unless that creature leaves combat, it continues to be a blocking creature through the end of combat step, even if the creature or creatures that it was blocking are no longer on the battlefield or have otherwise left combat by then.