Walk with Spirits cooldown is way too long its got double the duration and cooldown as Meld but only 1/4 the benefit its also a "capstone" destiny effect. So its not good as an "o ****" button. It could also be compared to Shadow Veil where you have the same benefit but have an uptime > cooldow.
IMO the design on this ability needs to be rethought out is it an "o ****" button (up the effect to at least 50%), or is it a defensive buff to make the tree more defensive (then make it work like shadow veil uptime >= cooldown)