Can akromas will disipate blockers?

Few questions for rules, we had l, lets say i have a crestue that deals 10 dmg and is blocked by a basic 1/1 token, if i use akromas will on that creature that attacks does that blocker just dissipate because akromas will gives protection, and another question can you use akromas will when opponent is declaring blockers but before he declares a blocker for that creature