Inspired by the Dude's online league format, I've come up with more limited-card pool variants.
Mage Block formats are similar to Set Block formats. A Mage block format is a variant in which only a particular set of mages are legal.
Here are some hopefully good examples of Four-Mage Block formats:
1. All core mages (pick only one element for wizard)
2. Arraxian Warlock, Priestess, Necromancer, Forcemaster
3. Johktari Beastmaster, Anvil throne warlord, Air wizard, malakai priest