Maplestory "High Five" Private Showcase

I can't remember, but if I have to guess 8% per symbol? (You use the symbols on an equipped symbol to increase its EXP)
The symbols I used were from the Road of Vanishing though, you also have other symbols from the other two maps, but they're unreleased at the moment. Maybe they give better EXP.

Oh they don't level like Reverse equipment? I thought they leveled from being equipped and just hunting mobs.