Rallying cry questions

Syiccal

Firstly does it give 5 seconds of 600 dmg amd 3200 resist as its 20 seconds proc with 15 seconds cool down.
Secondly does it stack in groups?

baselesschart

It gives 300 weapon damage and 300 spell damage. The buff lasts for 20 seconds with a cooldown of 15 seconds meaning you could theoretically have 100% uptime on it, but you wouldn't necessarily have 100% uptime. I also don't believe this would stack in a group if multiple people were running it, not that it really synergizes well with group play.