I did this with using some random 4*-5* Rescue cards in a mono deck.Generally all the powerful cards that are perma elo banned and you'd never touch them with a stick as far as DTs go. Due to an average of something like 7 damage 7 power per card and the ensuing +12 attack bonus, it was quite easy to 2 hit KO most of the time, thus managing 7 wins in a row and completing the mission. They have some crazy 1 HKO cards flying around there in Survivor T2 (like Kolos for example, the one I hate the most) but if you don't get overly excited or scared, you should be ok.
Woops brain fart i mean win 5 games in a row in survivor i can barly to that my self but get you best 4-5* an what othere sentenial cards you have an win. thought i think staing in survivor for all her checks be the best. you can win more in suvivor an make more damage.
Your not alone. It took me more around 3 hours for that event.
Considering I have more than 100% of the collection..
Anyway here are my TIPs:
1. Don't quit urban rivals. That's not the proper way of finishing a mission.
2. In my experience, it is advisable to play in Survivor ELO, and try using Damage Reducers + Attack manip 2 clan or mono clan deck. I'm always use to playing survivor t2 but due to instability, I wasted more than 2 hours there. In survivor ELO, it took me maybe 30mins.
3. Survivor ELO, since right now, a lot of elite players are still playing for the Ld with their elite cards. In survivor T2 I faced a DJ Korr buffed with an Ambre. Also a Kiki Cr.... the horror
4. Play in Odd Times, meaning some time like right now or earlier.(if you get me)
Hope that helps