Does Discharge have a damage cap?

When I put 5 gems into my 6 link armor for discharge, it shows the damage at 21 million on the character screen

No matter what gem I put in for the 6th, it shows -21 million damage and it just tells me how much mana it costs


Anybody know why that is? I'd like to add a 6th damage gem, but if it isn't doing anything then I guess it's a waste?

Hopefully it's just a glitch on the character screen

The character screen and the tooltip are really only useful before maps, when build complexity is low. I wouldn't trust it with anything even mildly involved like Discharge. Unless you messed up really badly, adding an extra link will increase your damage.

The only thing I can think of is if it's displaying 2.1 BILLION damage, and any extra damage on top of that causes it to overflow to the negative value.

If you want to find the effect of different support gems, use Path of Building (the community fork).