Round table

And which heroes of Rampart have the highest chance of getting Earth magic for mass slow (besides Inferno and Conflux)?

If we're talking about Shadow of Death, here are the points for Earth magic for different types of warrior heroes (out of 112):

Knight - 2
Ranger - 3
Alchemist - 3
Demoniac - 3
Death Knight - 4
Overlord - 3
Barbarian - 3
Beastmaster - 3
Planeswalker - 3

Almost all heroes have the same chance of getting Earth magic; Castle has the lowest, and Necropolis has the highest.