[Phanx]

Something like this:

--  Make a list of the buffs you want to check for:
local buffs = {
    ["Battle Shout"] = true,
    ["Blessing of Kings"] = true,
    ["Horn of Winter"] = true,
    ["Mark of the Wild"] = true,
    ["Well Fed"] = true,
}
 
------------------------------------------------------------------------
--  Create a frame.
--  Frames are the basic UI objects in WoW.
--  You need them in order to respond to events (things happening in the
--  game) or to show visible elements on the screen (graphics, text,
--  buttons, etc.).
------------------------------------------------------------------------
local frame = CreateFrame("Frame")
 
------------------------------------------------------------------------
--  Register for the UNIT_AURA event.
--  Events are how WoW tells addons that something has happened.
--  The UNIT_AURA event fires whenever any buff or debuff changes on any
--  unit that currently has a unit token (such as player, target, boss1,
--  focustarget, arena3, party2, or raid18pet).
------------------------------------------------------------------------
frame:RegisterEvent("UNIT_AURA")
 
------------------------------------------------------------------------
--  Set an OnEvent handler for the frame.
--  This is a function that will be run each time the frame receives
--  an event for which it has registered.
--  The function recieves a reference to the frame as its first
--  argument (conventionally named "self"), the name of the event
--  as the second argument (conventionally named "event"), and then
--  event-specific data from the third argument onward.
------------------------------------------------------------------------
frame:SetScript("OnEvent", function(self, event, ...)
    --------------------------------------------------------------------
    --  ... is called a vararg, and is a construct that contains any
    --  number of variables. It is used mainly when receiving variables
    --  without knowing how many of them there are. Since different
    --  events pass different numbers of arguments, a vararg is very
    --  common in event handling functions.
    --  Technically you don't need it here, since your frame is only
    --  registered for one event, but if you expand your addon later,
    --  it may become useful.
    --------------------------------------------------------------------
 
    --  Unpack the vararg into the variable(s) it contains:
    local unit = ...
 
    --  If the unit is not "player" you don't care about it, so
    --  you can quit out of the function early to save time:
    if unit ~= "player" then
        return
    end
 
    --  Loop through all of the buffs you want to check for:
    for buff in pairs(buffs) do
        --  Check to see if you have the buff:
        if UnitBuff("player", buff) then
            --  You have the buff.
            --  Do something here.
        else
            --  You don't have the buff.
            --  Do something here.
        end
    end
end)