So say...
If _source==Spriteling then 'Ignore' [not sure what to put in place of ignore] else "echo" [not sure here either... maybe echo, print, put, etc.] _type; end
If _type==Normal then usebagitem(117) else usebagitem(11

; End
Where "usebagitem(117)" is Physical Immune Potion and "usebagitem(11

" is Magical Immune Potion.
Or maybe as a macro with frame...
/run if Global _source Spriteling=true then SPRITE_CHAT_FRAME:AddMessage("Your own damage was ignored") end
/run if not Global _source Spriteling=false and _type Normal=true then usebagitem(117) else usebagitem(11

end
Any thoughts? I know that isn't right.