DN Zeta

So a zeta on DN's unique allows for Force Drain to more consistently reduce the cooldowns for Annihilate because it causes more enemy characters to have a debuff/negative status effect. If DN hits you with force drain and you don't have a debuff there's only a 50% likelihood Annhilate's cooldowns gets decreased, if you do have a debuff it's 100%.
So where the zeta is MOST helpful is on a team that otherwise isn't placing a lot of debuffs, your team is placing a ton of debuffs already.
The biggest thing to think about however is are you gonna star this character up? What if he goes F2P like Baze with a single hard node? That's a long farm on a single hard node from 3*. If it were me Id do it IF I was prepared to purchase some shards here and there to get him to 7* in a reasonable amount of time, but those are the factors I'd recommend you think about in coming to your own decision. Good luck bro!

I did, no regrets. It essentially gives your entire team +25% offense once applied and it really helps my SA get health below 50% for SO to overpower through full or near full protection.I run zMaul, zSavage, zNihilus, SA and EP. Been #1 since I upgraded the 3rd zeta.

I did because I found it useful when he is part of a Zaul team. I wouldn't say it is a gamechanger but it definitely has its uses for sure

I have Zader, Zaul, Zylo and zDN(unique) and I'd say it's my 2nd favorite zeta after Zylo. It pretty much guarantees that his annihilate will cool down, it will slow down the enemy and it makes enemies much easier to kill. I run him and Zylo on my Rex team and have no problem taking down teams with 3-4 zetas on it.

Zeta'd Wound in the Force as well, no regrets. But it does not have a huge impact. Running zMaul(L), zSavage, zDN, EP and Sith assassin. DN is more than viable at 4* :)