project-meteor-server/data/scripts/effects/blindside.lua

require("modifiers")
require("battleutils")

--Forces crit of a single WS action from rear.
function onPreAction(effect, caster, target, skill, action, actionContainer)
    --If action hit from the rear and is a weaponskill ation
    if (action.param == HitDirection.Rear and action.commandType == CommandType.WeaponSkill) then
        --Set action's crit rate to 100%
        action.critRate = 100.0;
    end

    --Remove status and add message 
    actionsList.AddAction(target.statusEffects.RemoveForBattleAction(effect));
end;