No, I tried, the turrets will not be able to kill Baron because his HP recovery rate is faster than the turrets' damage rate (even if there's 2 turrets). The real problem is that Baron doesn't realize that it's being attacked, it's just standing there. So while the Heim cannot abuse it to "kill" the Baron by itself, it can still be used as a free ward. As for Teemo's shrooms, it's inactive; it's not attacking the Baron, so Baron can ignore it. But the turrets are attacking Baron, so Baron should be attacking it back.