Scripts

Why not simplify the script and use mass casts? UnitCastGlobalSpell(GetAttackerHero(), SPELL_MASS_BLESS).

function Start()
local mana = GetUnitManaPoints(GetAttackerHero())
SetUnitManaPoints(GetAttackerHero(), 200)
sleep(1)
UnitCastGlobalSpell(GetAttackerHero(), SPELL_MASS_BLESS)
sleep(1)
end

Your script probably lacks sleep commands within the for loop; after all, casting functions take time to execute, and it's a noticeable amount of time.