I've been buying nothing but a Spirit Visage for MR in most of my games
Even against magic heavy teams. There's three problems here:
- The only decent MR items build out of Spectre's Cowl and the others are pretty much geared towards supports and bruisers exclusively.
- You can completely shut down a mage's damage output with that single item. Wasn't this why you removed Force of Nature?
- Armor items synergize with themselves and are tuned as such to a point where you have to buy a bunch of them to get value out of them. Looking at Thornmail and Frozen Gauntlet especially.