Tooltip says “30% chance on any … attack” but from testing it seems like around 3%. It procs very rarely, sometimes not at all during a fight.
on my enh shammy it procs all the damn time, but mostly from melee attacks instead of spells
From my testing the earth is flat … maybe 3% round as it’s not noticeable at all.
According to comments on wowhead from way back, there is a 45 sec hidden cooldown…