A friend of mine is running a small (max 20 people) Fantasy Tournament at Fantom Fest in San Antonio, TX at the end of September. I believe it's an $11 entry fee. If any one is interested there is more information here http://www.fantomfest.com/#!gaming-room/c233f
Yeah. It kind of a poorly written house rule. The 4+ limit only apply when you are using a ward to save against a "no saves if any kind" spell. So you can have a 2+ ward and use it as normal. But if you get hit with dwellers you only get a 4+ ward against it (which is better than no ward!) It makes the 6-spells about half as effective against characters and units that you pay for MR.
I actually kind of like that. Makes the big nasty spells still good at obliterating uber units, but gives your characters a bit if a cushion. Neat.