Possible bug with Rageforged using more than 10 Rage?

Rageforged support says "Supported skills spend 10 rage if possible to deal 35% more damage"

This works fine in most cases, but I've noticed when I link it to Armour Explosion suddenly I get massive rage drain.

1 Click = 50 rage spent

It's like everytime Armor Explosion triggers it repeatedly costs me rage for all the enemies that explode. Is it meant to be like this? The way its worded does not sound like it. It sounds like 1 click = 10 rage spent.