Honestly, a tank is the least of my worries. Moreover, I do recommend magic resist items. If you can't be bothered to read the items section, why bother commenting at all?

This looks like a decent build and all, but I'm just not liking the lack of armor and magic resist you have. Say you're going up against an Amumu. What are you going to do? Since he lowers your magic resist by up to 30 points, that takes you down to about 80 magic resist, and if he plays like i do, he penetrates another 15% of that, he would just tear you up with tantrum, since it does a fixed amount of damage plus up to 2.7% of the targets max HP. My suggestion would be to get a Banshee's Veil as well as a FoN, and maybe a Malady? You would survive a lot better that way imo.