Mages "Farm" spell needs a minion execute added to them
Its stupid that AD wave clear champs can clear waves and CS very easily early game. But AP champs cant do the same until late mid game.
I find that Swains Q will leave minions with JUST enough HP so your wave will kill them before your Q is up again but Enough that Swains Auto attacks will not kill them with one last hit.
Now if Riot adds AP% to mages Auto attacks this would not be an issue I think. But right now CSing as a Mage vs a AD champ mid lane is painful.