Based on an old post for someone who currently resigned from the fandom I cannot find.
B: Original and default of course. Stanard necromancy, infection and carnomancy, albeit so corrupt even normal necromancers like Liliana hate it.
G: Not see a lot, but from Vorinclex's take it involves carnomancy, usually to assimilate creatures unto itself or gestate new things
U: Mostly mind magic from what can be seen. Gin-Jitaxias surprisingly uses few combat spells.
W: Mostly focused on porcelain shards and bones. Abundant use of photokinesis both in cards and in Norn's battle against Ashiok.
R: Mostly fire, lava and metal magic. Probably the hint that its the least corrupt.