Greetings, mate! Fellow "Reaper" destro here, i want to share some of the things i found out until now, I hope they may be of use to you.
Scar debuff: In order to stack this debuff on the target, you need to have your shield up and get hit. When you stack it up, your spins and execute/annihilation restore hp equal to 20-30% of the dmg they deal. Keep in mind, that you can stack it by getting hit, that means for example last boss in desolate tomb does his fire breath attack, you stand in it and it's instant 5 stacks, because it consists of multiple small hits. In pvp it's harder to pull it off, because you can activate some nasty skill on the enemy when you get your shield up. If it stacks while you have iron plating up (haven't tested it yet), then it should be easy to stack it to 5 in pvp (stand in aoe and do V-V fast to get invul. ) and at 5 stacks you can spin or annihilate to heal up (don't forget to hold annihilate for 2 sec, the last hit deals huge dmg). But ye, i agree that the tooltips are not very useful ...
About the passives, the one that gives you 100ap and 35% mystic dmg while fury is up is overpowered in my opinion, since now you can reset fury with grab (instant reset on massive enemy, -4sec cd on LMB while grabbed), soo this is very good dps boost, paired with the +2 sec duration on fury it seems very strong. The other one is good for pve, keep in mind that rmb is 2 attacks, so 4% is not that low, since you deal a lot of them already, and if you happen to hit multiple targets, it gets some decent resets :D (don't forget rmb is aoe).Useless for pvp, but not big deal... especially since we both don't do much pvp ...
Emberstomp: it's not a dmg skill, never was serious threat. Tho you can spec into "Umbrastomp" or whatever it's called (pink stomp), then it deals all the dmg instant, gives you better modifiers on RMB, and stays as a buff, not area on the ground that you need to stay in. BUT - you loose the overpowernesnes of the non-talented spell, that has merged the dmg bonus and the +400% defense and most cc immunity, and in pve even tho you get +30% on RMB over the default stomp, you loose on possible weapon resets from the dot. So, if you can force someone to trinket your grab because of emberstomp, then it should be good times for you (you can stunlock and use the real dmg skills like annihilate. If they don't, just use it like temp cc immune and dmg reduce.
@Arohk I think they will nerf them, both spins look op now, blue spin combines all 3 talents from before (+500% bonus defense, +XX% flat dmg reduce, +80% movespeed, parry multiple attacks), and red spin got serious buffs too, and it has badge that makes it pull enemies to the destroyer. Sadly, i'm super low on gear so i cannot tell if they really are OP in pvp.
Overall, i'm pretty happy how shadow destro awakening is, i spec all 1 from the talents, give Repulse,galeforce,awakened galeforce +5 hm points, and enjoy the lazy gameplay :) (I'd advise not to spec annihilate for pve, yes, it deals x3 times the dmg of the execute, but still is far worse in my opinion - you need to stand still for 2 sec, it doesnt refresh your badge as it says in the description, which leads to dps loss in the end - according to my testing). Don't forget that now every third galeforce resets and enables galeforce :D (RMB->RMB->F->RMB->RMB->F->RMB->RMB->F->F->...).
P.S. Don't take anything i say for granted, i may have played destroyer for a while, but i'm casual f2p, sooo i'm open for corrections and additional information too.
GLHF