[Fizzlemizz]

It's a bit of a loaded question as it's missing details (most of which probably come with WeakAuras). You could start with something like:

local spellID, SnDID = 315496 -- S&D
local _, _, icon = GetSpellInfo(spellID) 
 
local f = CreateFrame("Frame", "Kovexpulthul_Buff", PlayerFrame, "AuraButtonArtTemplate")
f:Hide()
f:SetSize(40, 40)
f.Icon:SetTexture(icon)
f:SetPoint("RIGHT", PlayerFrame, "LEFT", 0, 0)
f:RegisterEvent("UNIT_AURA")
f:SetScript("OnEvent", function(self, event, ...)
    local unit, auraInfo = ...
    local added, updated, removed, full = auraInfo.addedAuras, auraInfo.updatedAuraInstanceIDs, auraInfo.removedAuraInstanceIDs, auraInfo.isFullUpdate
    if added then
        for k, v in pairs(added) do
            if v.spellId == spellID then
                SnDID = v.auraInstanceID
                self:Show()
                break
            end
        end
    end
    if removed then
        for k, id in pairs(removed) do
            if id == SnDID then
                SnDID = nil
                self:Hide()
                break
            end
        end
    end
end)

It's been a while since I looked at auras so there may well be a better way.