It's 7yalms, which means it only works if characters are stacked.
It can't be used on a target, so you can't place it on a tank for tank busters.
It lasts 15 seconds, which is pretty short when you consider the length of most utility.
And it's on a 2 minute Cooldown, which is ridiculously long when you consider my h better stuff like Hypercharge is less than that.
What exactly is the point of mantra? It's range, CD, and duration is all so limited you can barely plan around it unless you use it as a prepull buff or before a bosses ultimate.
It feels like a rather forgotten tool to me.