I just found out wear Death Knight's Anguish - Thottbot: World of Warcraft and if you get the Item - Death Knight's Anguish Base - Thottbot: World of Warcraft effect, it stacks when you mount up.
Preety useless for me but maybe not for the others
EDIT: I found out that this works only with the paladin charger because it's a spell
EDIT 2:here is a screenshot as a proof